The most common launch mistake is building features around a checkout that has never charged anyone. The first paid hour is a stricter test: a visitor checks out, the webhook persists a subscription, the entitlement appears in the account, and a support question about that purchase can be answered without leaving the product.
When that loop works, every later feature inherits trust. When it does not, no amount of surface area hides the missing link — and you will discover it in public, from a customer.
So design the hour before the roadmap: pricing that explains itself, a checkout you have replayed in test mode, a visible account state after payment, and a support path that reaches a human. Metrics can wait.