At what point do/did you feel comfortable enough to launch?

I've worked with a bunch of early stage founders over the years and the right point to start telling people about what you're building seems more art than science. My rule of thumb for: Subscription model: When you have 5 people who pay you, and pay you again, and don't hate you. One-off purchases: When one person buys, and tells someone else, and they also buy. It doesn't at all mean your product/service is perfect. Now you know people will pay as you build. You're that valuable. Do you have a different process/marker? Please share!