I had my facial surgery 10 months after starting HRT, and would have had it sooner if it had been practical.
HRT will not change the underlying bony structures of your face. It can help with complexion and skin quality, and may even change fat distribution, but things like a brow ridge, overly large nose, square jaw and chin, none of that will change without facial work.
I knew when I started transition that facial surgery was one of my top priorities (along with beard removal and voice retraining -- and again, HRT doesn't really help with those, either) given the shape of my face back then, despite being passable. But I did all that because my dysphoria was such that I could not abide any kind of misgendering; I refuse to be clocked (which is also why I practice non-disclosure). And it was so important to just how I saw myself, too.