Ask HN: How do I gradually roll out a new app? Plz help

So heres my problem.

We're launching a new app this month and want to roll out in phases. We want 1% of the users to use the app the first week. We want another 10% the next, then 40, then 80... you get the point.

I'm trying to find a tool to help us do this. Something like Google Optimize for split traffic? Or perhaps another tool for creating user groups and assigning them to a certain path.

Does anyone have any good ideas or have you done this in the past.

I could really use some help.