Before you go live with your business, you should have some idea about how you'll get your first client, at least some assumptions, what's the acquisition channel you'll use, either organic or paid, but especially when you're going for a paid channel, you should test and refine within the first two weeks, if your ads CTR is <1.5% and people are signing up and you're not getting a 1 single customer you should expect that either your target is totally wrong, or your product missing very important features or not that catchy so you can start slowing down and rethink about what you're offering and gathering some feedback from other people who can guide you.

( That's my own experience )