I have no in-app prompting at all, and I have a simple 5-email benefits-oriented email series (via customer.io).

I don't have enough numbers for things to be meaningful (it's a small-scale SaaS), but I seem to recall that removing the CC without onboarding initially was not great, and things improved with the onboarding tour (sorry if I cannot be much more specific!).

Removing the CC avoided the need to handle refunds for some people, which was a bit of hassle to handle.