I think I was on estrogen for like 4 years before I started? no particular reason for the wait, just how it happened to pan out. got on progesterone ~10 months ago and been on E since 2020. idk how much waiting several years affected my results, but i've definitely had breast growth up to this point on 100mg. and if the feeling in my tits is any indication, i'm gonna be having more breast growth on 200mg.

iirc common wisdom is to start it a year into being on E. haven't read up on it in forever so idk. people's experience varies a lot just from what i hear talking with friends. for me i got annoyingly horny and my tits went up a cup size or two (didn't measure, just guessing). i think it also increased appetite for me, and gaining a bit of weight probably helped with fat distribution and breast growth. hard to say how much effect prog really had, but look at side-by-side pics of my tits before prog versus after 10 months of it and there's definitely a difference.

i think if you've been on E for a year or more and you're wanting more changes, prog might have an effect and it might not. i had no adverse effects from it, unless you count being inconveniently horny as an adverse effect, and i think it's generally regarded as very low risk. overall i'm happy with my experience.