I think its usually super important to wait till you've been on hormones for at least 2-3 years (unless you have some feature of bone structure that is soo incredibly prominent that you know it will need correcting, like a humongous chin that's prominent for even a man or something)
I thought I would need FFS but after being on hormones for 11 months, I can safely say I do not think I need it.
(but again, thats just me)
Also a lot of FFS surgeons have a kind of "dogma" around it where they all say "let's obliterate that jaw and lower that hairline), but a lot of incredibly beautiful women have prominent/square chins and jaws and high hairlines (Think angelina jolie or kristen davis) (and also the hairline may lower on hrt and chin/jaw will def soften/round a little)
and also, even the nose can change its appearance in a minimal way with hormones (i've found my nose looks a tad less bulbous)
Wait till the soft tissue has really shifted. Similar to breast augmentation you will get better FFS results if you and your surgeon can see already what your face will look like. I have seen some bad cases where girls with resources get intense FFS done like a year or 6 months into transition and the soft tissue shifts so that they now look like they have no bones!
the obviously male features (a prominent brow bone for instance) may become less noticeable too! however, if after 3 years your brow bone is significant than I think that can definitely be shaved down (though you have to think about the new forehead in relation to the nose and all the other features). But so much about the face might change.
If you do get it, my advice (after researching this for months)
Don't go to Zukowski!
Preferably go to a plastic surgeon who also is certified in cranio facial and/or maxilo facial surgery (and maybe dentistry if they will be working on your jaw/chin!)
ideally you would see imaging beforehand (preferably 3-d), to give a rough estimate of what you'll see
Depending on how much work you need done it might be best to work incrementally. If you absolutely can't stand your nose but are sort of ok with other stuff then go to a surgeon who really Specializes in natural rhinoplasty first maybe. (then you could see an ffs surgeon to bring other features in alignment if necessary)
and with all of these surgeons if you feel like you just "don't like them", or that they are not treating you in an individualized way that's not good! (I waited 4 months to see Dr. Harrison Lee for a consult which was 10 minutes!) BE VOCAL about what you do and DON'T want with them and also find a way to reach out to patients who have seen them and get pictures from them not just the office
Also remember, you are already, always beautiful!