A common pattern is "wait some amount of time, then check a condition before sending." For example, if you run an NBC Page program application funnel, you might want to send a 24-hour reminder only to applicants who haven't yet finished their orientation paperwork.
Buttondown's automation filters are evaluated once, at the time the trigger fires — they don't re-evaluate mid-sequence. This means a single automation can't do "wait 24 hours, then check metadata." But you can achieve the same result with two automations working in parallel.
Automation 1 — Reminder for incomplete applications:
Automation 2 — Welcome for completed applications:
When a subscriber is created without the orientation_complete flag, Automation 1 queues the reminder. If they finish orientation later, Automation 2 fires and sends the welcome content.
Using the API for precise timing
For even more control, you can skip the timed automation entirely and have your external tool (Zapier, a script, etc.) check the condition after the delay and then invoke an automation via the API only if the condition is met.