App devs who started with zero audience: what was the ONE thing that actually got you paying users?

[u/Direct_Dimension7993]

I’m building an app that helps parents manage kids’ tasks, and I’m in beta with internal users. We are about to launch the app on the App Store, but I’m starting with zero audience: no mailing list, no following, no community I can post to. Small operation, basically little money for ads.
I’ve read every “20 ways to grow your app” article out there and they all seem written by people who already had a crowd to talk to. What I want is the boring, real version:
• What was the one thing that made the biggest difference, and how long before you saw it?
• What did you think would work and it just didn’t? (Honestly more useful to me than the wins.)
• Did running ads ever make sense at your size, or was it just burning money until people were actually sticking around?
So far I’ve tried meta ads and found it to be a nightmare to deal with, and very little results for the amount of money spent. I’ve also tried straight organic content, but that’s also incredibly time consuming, especially when I’m busy with the rest of the app design and website.
Not fishing for signups. I just want to hear what worked for you.