Personally, I think that if it's true gynecomastia, it's a bit of a head start but also implies that there *may* be a greater sensitivity to estrogen.
I had true gynecomastia, and not only did I see visible growth within the first week on a very very low dose (think significantly lower than the bottom of the range suggested for transition) but I've ended up 42DDD. So it worked for me, anyway. 🙂