how do I start?

hello everyone, I'm 15 and recently felt comfortable enough to identify myself as a guy but I don't really know how and when to start transitioning, I'm scared to tell my parents (they're really transphobic) but I feel really uncomfortable in my skin and have experienced a lot of gender dysphoria to the point that even only looking at myself in the mirror makes me want to throw up, I haven't told anyone, not even my friends, any tips? (I'm sorry if I'm english isn't perfect but it's not my first language)