Where do you find your target audience for a soft-launch?

Hey hackers,

Hope you all had a great start of the week!

After getting some feedback on one of my last posts/questions, I wrapped up the most critical parts of my app and I rolled it out to a very small subset of users (mostly friends), to gather some initial feedback. I got some really good insights, addressed them, and now I want to roll this out to another subset of users (still rolling out in phases, to small subsets of users).

Question I'm struggling with now is - where do you find the right audience for your product, to ask them to play with it? I feel like I'm not 100% ready to roll this out to public, but I'd be happy to get 10-20 people on board to start playing with it. Any hints where/how to find those people?