When did you start paid marketing and ads?

My co-founder and I recently launched Orbiter. It's a dead-simple tool for hosting static websites and web apps. We're currently focused on doing the hard, dirty work of attracting customers. It's working well as we already have 3 paying customers and more than 40 websites live a little more than a week since our launch.

Something I'm thinking about though is what signals the time for us to lean into paid marketing and ads. For those that have started with "hand-to-hand combat" to get customers and transitioned successfully into paid marketing, what was your criteria and how did it work out for you?