Milestones, not days
Your product posts a webhook when a user hits a milestone. The activation sequence branches on the tag that webhook creates, so a user who activated on day one skips the nudges and a user who has not activated by day three gets a different, more specific message.
Split self-serve from sales-assisted early
One question on signup — company size — decides whether the visitor lands on the trial or on the demo calendar. Sending a fifty-seat prospect through a self-serve trial is the most common way SaaS funnels lose their largest deals.
The expiry ladder and the win-back
Three touches around expiry, then silence, then a single win-back thirty days later with a genuine reason to return — usually a shipped feature. That win-back typically recovers a few points of the trial base for the cost of one email.