Day one, after they pay
Within an hour of signing up, before doubt sets in
Hi [name] — glad you're in. Here's what happens next. Your plan is on your phone at [link]. Add it to your home screen so it's one tap. Week one is three sessions, thirty minutes each, and nothing you don't already have at home. It's deliberately easy — I'd rather you finish it than be impressed by it. Log each session as you do it, even if you change something. What you actually did is more useful to me than what I planned. Sunday I'll ask you four questions and we'll adjust. That's the whole rhythm.