How many chapters do you write before posting?

I've been writing a new fic idea that's grabbed my mind, and so far have managed to write three chapters so far. I'm about to start the 4th chapter, but I wanted to ask for other others. How many chapters do you write before posting? Or do you post after you finish your first chapter?

I'm going back and forth between whether to post, or if I should wait a bit longer before posting the fic. So I wanted to hear how others approach posting their fics.

Thanks!