They gave users a 30 day trial period, so starting on launch day, they had precisely 30 days to get billing sorted out if they hoped to be able to charge anyone.
A free trial period may or may not be suitable for your product. But you can probably get by without it on launch day.
You could even launch in beta mode and give people access in exchange for feedback.
If you're targeting graphic designers, then go ahead and tweak that CSS. Otherwise, go ahead and get some real people using it. If they're using it to solve a pain point, they'll quickly tell you what's good and what's not. And if they don't use it at all...well, that's valuable feedback too.