I've seen a lot of changes in the past 40 years. Lately there is this prevailing mythology that before you can even think of going full-time you MUST do A - B - C - D etc.. Nothing can be left out. It is like the only way possible. Not at all what many TSs I knew in the the 70's could even dream of doing. All this technology is just a tool to make doing the work easier.
The only criteria for going full-time I can imagine is "When you want to, or need to" Anything else is just gravy. Plenty of TSs have forged ahead with doing nothing more than just presenting as female. No HRT, no FFS, no electrolysis, no voice coaching, no years or months of therap, et al.
Yes, all these things can help in passing. But if the time comes when you need to, it makes no sense to wait and live a miserable life, that is if you choose the latter, living.