Black Friday Waitlist in Klaviyo: Form, List and Flow

This blog recommends opening a Black Friday waitlist in October: the Q4 2026 promotional calendar and the October email ideas set out the principle and the dates. What remains is the build in Klaviyo, which comes down to five decisions: dedicated list or not, consent, form, confirmation flow, and how to use the list on early access day. Each has its own trap, and the traps are documented.

Black Friday 2026 falls on Friday, November 27, the day after a Thanksgiving set on November 26 by the US federal calendar (Federal Reserve, K.8). The earlier in October the list opens, the more weeks it has to fill before that date.

TL;DR. A Klaviyo waitlist has four parts: a dedicated list, a form that subscribes people to it with explicit consent, a flow triggered by joining the list, and an early access campaign that includes the list. Three documented facts are worth knowing before you publish. Importing profiles into the list triggers the flow for the whole file. An unchecked consent checkbox does not stop the subscription in a Klaviyo form. A European visitor who has not consented to tracking is not identified, so they see a form designed for strangers.

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What the waitlist has to produce

An audience that asked to receive early access by email, with a known sign-up date and source. It complements the VIP segment in our guide to the 9 segments, which is calculated from purchase history: the list gathers people, customers or not, who raised their hand themselves.

What the form promises has to be delivered, and the discount level should not be revealed at this stage: an overly precise teaser gives people a reason to wait until November 27.

Decision 1: a dedicated list, next to the main list

Klaviyo recommends one main list per channel, completed by additional lists as needed, and by segments to personalize the experience (Klaviyo, one main list per channel). For the waitlist, three documented reasons justify a separate list.

• A form can subscribe people to a list, not to a segment: a segment fills itself through its conditions (Klaviyo, lists and segments).
• A list-triggered flow starts when a person joins the list for the first time (Klaviyo, list-triggered flows). A customer already on the main list who fills in a form connected to that same list does not join it a second time. With a dedicated list, they do join it.
• A list can be isolated with the If someone is in or not in a list condition, which can be filtered by the date the person was added (Klaviyo, segment conditions reference).

The trade-off is documented: the same profile can end up on two lists, and separate campaigns to those lists repeat messages. Within a single campaign, Klaviyo does not send the same email twice to a profile that appears on several lists (Klaviyo, one main list per channel). The rule follows: BFCM sends include both lists in the same campaign, or exclude one of them. The details are in BFCM Segments in Klaviyo: Exclusions, Overlaps, Skipped Profiles.

We go with the dedicated list, because the confirmation flow depends on it. The opposite choice remains coherent if you give up the flow.

Decision 2: consent

For brands emailing consumers in France, the CNIL requires prior consent that is free, specific, informed and unambiguous. It calls for a positive and specific action, and the example given is a dedicated checkbox that is not pre-ticked. Accepting general terms is not enough. The page offers a model wording, of which this is the email variant: "I agree that my information may be used for commercial prospecting by email" (CNIL, commercial prospecting by email, page updated June 10, 2026; the English rendering is ours).

Two consequences for a waitlist.

Consent is specific, so the form's wording fixes the use. Decide before publishing whether the list serves the operation alone or your marketing emails in general, and write it into the wording.

The exception for existing customers, which covers similar products or services, assumes a sale took place. The CNIL specifies that it cannot be invoked when the customer merely created an online account. Account holders with no order therefore fall under consent: one more reason to invite them to sign up themselves.

On the Klaviyo side, four points matter (Klaviyo, collecting GDPR-compliant consent).

• When you create a form, the Enable Data Protection Fields option provides a template with GDPR wording that you can edit.
• The boxes a visitor ticks are stored in the profile's $consent property. Klaviyo states that checkboxes should not be pre-checked.
• People who submit the form are subscribed even if the checkbox is not ticked. The page asks you to segment on the property tied to the checkbox to identify those who consented. Any send that assumes the checkbox should therefore filter on that property.
• Klaviyo records the form ID, the method, the form version and the timestamp, and keeps the exact text of each form version, which support can provide.

Double opt-in is set at list level. Only subscribers who confirm are added to the list and queued for the flow, the confirmation email stays valid for 72 hours, and a person who does not confirm leaves a blank profile with no list membership (Klaviyo, the double opt-in process). Klaviyo's GDPR page lists it among its best practices. The CNIL page does not mention it: the trade-offs are detailed in Double Opt-In: How to Implement It Without Killing Conversion.

Decision 3: the form

Type and placement

Klaviyo describes five form types (Klaviyo, getting started with sign-up forms). The popup catches the eye but can disrupt browsing. The flyout stays visible without blocking. The full page form can serve as a dedicated sign-up page. The embed sits in a section of the site, and for a footer embed Klaviyo suggests asking for the email only. The banner can open another form when clicked.

The combination that follows for the waitlist: a popup or a flyout on traffic pages, a banner that opens that form while the operation is being prepared, and an embed in the footer. Every list also has a Klaviyo-hosted subscribe page that can be customized list by list, and whose link can be shared in emails or on social media (Klaviyo, sign-up forms and subscribe pages).

Timing, frequency, priority

Display is set in the Targeting & behaviors tab (Klaviyo, form targeting and behavior settings). The available rules are exit intent, a time delay, scrolling and a number of pages viewed, with a switch to require that all the selected rules are met. Frequency is set by a number of days before the form reappears after being closed, and by a box that hides the form after a submission. These settings rely on Klaviyo's cookie: a visitor who clears it or browses privately may see the form again.

For an exit-intent form, the getting-started page suggests showing the form again 5 days after it is closed and stopping after a submission (Klaviyo, getting started with sign-up forms). When several forms can appear for the same visitor, for example a generic welcome form and the waitlist form, display priority (Low, Medium by default, High, Highest) decides which one goes first. At equal priority, the order is not guaranteed.

Targeting

To hide the form from people already on the waitlist, the Show to specific profiles in a list or segment option offers Exclude these lists and segments. Membership changes are then reflected in the targeting automatically. The Don't show to existing Klaviyo profiles option, handy for a welcome form, also hides the form from known customers, who are the most valuable audience for early access.

One trap concerns European visitors. Depending on Shopify's privacy settings, Klaviyo may not track the onsite events of a visitor in the EU, the EEA, the UK or Switzerland who has not consented. That visitor is then not identified. They see the form with Don't show to existing Klaviyo profiles, and with the exclusion of a list, since they are not known as a member. They do not see a form reserved for members of a list or segment, even if they belong to it. Location targeting is not affected. Plan for already-known subscribers to see the form again: the documentation says a second submission creates neither a new subscription nor a duplicate in the list (Klaviyo, the Subscribed to List metric).

URL targeting accepts Containing and Exactly matching modes and a * wildcard. UTM targeting applies AND logic across parameters. An option stores the UTM parameters on the profile after consent, which gives you the sign-up source for segmentation.

Blocks and fields

Two blocks serve the waitlist (Klaviyo, form blocks and fields).

The countdown timer (Klaviyo, countdown timer in a sign-up form) comes in two modes. The fixed date mode counts down to a precise moment; the page gives the example of a VIP sale starting at midnight on a set date, with an end date up to 100 days ahead. The variable mode restarts from the chosen duration on every page load: it represents no real deadline, and only the fixed mode is consistent with a dated opening.

The sign-up counter displays the number of people who signed up over 30 days, 7 days, 24 hours or one hour, provided they reach the success step. It stays hidden until a minimum number of submissions that you set is exceeded.

A choice field (radio buttons, multiple checkboxes, dropdown) stores the answer in a profile property. A single question, for example the category the visitor cares about, lets you personalize the early access announcement later. Collecting declared data is covered in Zero-Party Data: Collect and Activate It Without Compliance Risk.

Submission

The submit button carries the Submit form action, the list to subscribe to (List to Submit) and the next step. To change the list later, you have to edit this button and republish, otherwise new subscribers keep going to the old one. Every form has a default hidden field, $source, that indicates how the person was added. This field and other hidden fields can be renamed, and a hidden field overwrites the value already on the profile at each submission (Klaviyo, form blocks and fields). A simple value without accents, such as bfcm-2026-waitlist, avoids case errors in segments, which are case-sensitive.

Two technical points: Klaviyo enables bot protection, including a CAPTCHA, on forms that collect an email or a phone number, and an ad blocker can stop the form from displaying or submitting. Test in a private window without a blocker, meeting all the trigger conditions.

Decision 4: the confirmation flow

The flow triggers on Added to list, with the waitlist as the reference list (Klaviyo, list-triggered flows). According to the page, the re-entry setting for a list trigger defaults to No re-entry, and Klaviyo notes that this setting is still rolling out. The first message goes out immediately: the getting-started page for forms recommends that the first email of a sign-up flow be sent right away (Klaviyo, getting started with sign-up forms).

A single email is enough: it confirms the sign-up and says what the person will receive and through which channel. Without double opt-in, the message goes out at sign-up. With double opt-in, the flow only starts after confirmation, since only confirmation adds the person to the list.

The documented traps of list-based triggering (Klaviyo, troubleshooting a list-triggered flow):

• importing profiles into the list triggers the flow for each of them: Klaviyo advises turning off the flows triggered by that list before the import;
• the Add to list option on a profile page does not trigger the flow, whereas Quick add does, without going through double opt-in;
• merging profiles or lists does not trigger the flow either;
• a message in Draft status sends nothing and queues nobody, a message in Manual queues profiles without sending, and only Live sends;
• an unsubscribed profile does not receive a flow's emails unless it is marked transactional;
• a form that is in draft, or connected to another list, does not feed the flow.

Klaviyo advises against triggering a flow on the Subscribed to List metric and recommends the list-triggered flow instead (Klaviyo, the Subscribed to List metric). If you use that metric anyway, you need a trigger filter on the list concerned.

To test, set the message to Manual, subscribe a test address, open Recipient activity then Needs Review, and send the message by hand. Then switch to Live.

Decision 5: early access day

Early access goes out as one campaign that includes the waitlist and the VIP segment, and excludes recent purchasers. The campaign is scheduled with Determine recipients at send time checked: without it, last week's sign-ups, who belong to the audience at send time, are missing from the snapshot taken when you schedule. The full mechanics (deduplication, exclusions, skipped profiles, Smart Sending) are in BFCM Segments in Klaviyo: Exclusions, Overlaps, Skipped Profiles.

One decision remains before launch: do sign-ups also receive the public opening? If not, the list goes in the Don't send to field of that campaign.

After Black Friday

Once the operation is over, set the flow message to Draft and unpublish the form, so the list does not keep sending a "Black Friday" confirmation in January. What happens to the list next depends on the consent wording: if you wrote that it served the operation, settle its fate according to that text. Merging the list into the main list does not trigger a flow. For sign-ups who never opened anything, the sunset flow is the usual next step.

Measuring in Klaviyo

Every list has a growth report, in the list's List growth tab (Klaviyo, one main list per channel). The page on the Subscribed to List metric also gives a segment for counting recent arrivals: the person is in the list AND subscribed to the list at least once in the last 14 days. The form's own results are read in form analytics.

Launch checklist

1. The waitlist exists, separate from the main list, and the form is connected to it.
2. The consent wording fixes the list's use, with no pre-ticked box.
3. Sends that assume a consent checkbox filter on the $consent property.
4. Double opt-in is decided, and the flow is tested knowing its effect on triggering.
5. The form's targeting excludes the waitlist, and its priority is set if another form coexists.
6. The behavior for unidentified European visitors is understood.
7. The hidden $source field carries a simple value without accents.
8. The flow is triggered by Added to list, tested in Manual and then switched to Live.
9. No import into the list is run without turning the flow off first.
10. The form's closing date and the list's fate after the operation are written down.

FAQ

Do I need a dedicated list, or is a segment enough?

A form only subscribes people to a list. A segment then identifies people who are already in the account. To have a confirmation flow that triggers even for a customer who is already subscribed, a dedicated list is necessary. Without a flow, a main list and a hidden field are enough.

What happens if an existing subscriber fills in the form?

Klaviyo does not record an extra subscription and does not add them to the list again. The form's hidden fields, however, overwrite values already on the profile.

Is double opt-in mandatory for the waitlist?

The CNIL page on email prospecting does not mention it: it requires free, specific, informed and unambiguous consent. Klaviyo lists it among its GDPR best practices. It is a deliverability and proof decision, and its cost is a flow that only starts after confirmation.

Can I import my customers into the waitlist?

Technically yes, but the import triggers the flow for the whole file and does not go through double opt-in. On substance, the CNIL's customer exception assumes a sale and only applies to similar products or services: an account with no order does not support it. Invite your customers to sign up instead, by email, with the link to the list's subscribe page.

When should the waitlist open?

Our calendars open the list in early October, in the weeks of the 5th and the 12th, and place early access in the week of November 16, ahead of Black Friday on November 27. A later opening leaves the list less time to fill, with no other technical constraint.

Want an outside look at your waitlist before it opens? Talk to the Deliver team or book a Q4 readiness audit.