Certainly, I would have started way, way, way sooner. If I could leave a note today for my much younger self, I would tell her not to fight it, that transgender is not nearly as uncommon as I thought, that is is not shameful, and that it is what I am. That information would have allowed me to transition earlier.
I might not be quite as quick to go for GCS, though. In the end, I would probably got for it again, because I did need it, but I'd have to give it more thought. My recovery was much longer and more painful than I had anticipated.