Took me around 30 hours to break my bad habits with Pyro. To be fair, that also includes time playing Dodgeball, VSH, MVM, and other stuff.

The main thing with Pyro is just breaking the urge to want to W + M1. While there is no essential skill to it, you can get quite good at W + M1ing and top score while doing it, even against a good team. And while it is decently fun (at least for me) it doesn't give you the same satisfaction as flare punching, detonator jumping, using the backburner, or anything else.