Custom Starting Date for Subscriptions

Hi guys,

Does anyone know how to create a subscription in Fluent Forms (Pro) where the start date is custom / user-defined?

Here’s what I’m trying to achieve:

I’m building a website for a mosque, and for Ramadan 2026 they want to let donors set up recurring donations that run for:

• the full month (30 days), or
• the last 10 days, or
• a custom date range within Ramadan.

I’ve seen the Scheduling option in the form settings. For now, my workaround is to create 2–3 separate forms (one per donation period) and set a fixed start date for each form.

But ideally, donors should be able to choose their own option inside a single form (full month / last 10 days / custom range), and the subscription should automatically start and stop based on that selection.

Any ideas on how to do this with Fluent Forms (or via an integration/workaround)?