Want to know something about google ads

after how many users should i add admob ads in my app.
please everyone leave you suggestions.

This is just my suggestion. Get at least 100 daily active users then place ads in your app. It would be better to wait for 200+, but 100 is ok. Just make sure your app has sufficient unique content and is interesting enough for people to continue to use once you include ads as some of them will be annoyed and be tempted to leave.

Also make sure you follow Kodular and Google’s policies for monetising apps.