I built and launched an app. It flopped. Now trying to learn marketing with minimal time.

Hi everyone,
I'm a developer who finally launched a mobile app this January after months of evening work. I didn’t promote it anywhere — no Product Hunt, no Indie Hackers, nothing. Just published it and waited.

4 months later: 20 installs, zero retention. Everyone who installed it quickly uninstalled.
Not great.

Now I’m trying to get serious about marketing — but I don’t want to lose too much time for coding. I work full-time and build my projects during evenings, so I can realistically spare maybe 30–60 minutes per day on promotion.

Here’s what I came up with:
Submit once to Product Hunt, BetaList, Uneed, AlternativeTo, AppAdvice
Post weekly updates here on IH
Be active on Reddit (comments in relevant subreddits like financialindependence, personalfinance, AndroidApps, etc.)
Comment/like on Product Hunt a few times a week
Try Quora if a relevant question comes up
Maybe experiment with X or TikTok later

This is all still new for me, and I’d love to hear from others:
What did you do first when your app had no traction?
Which of these actually helped you get early users?
What’s sustainable long-term when you’ve got limited hours?

Any advice would mean a lot. I'm not trying to explode overnight — just looking for the slow, steady path forward. Thanks!