I never had a problem with acne, but I have known lots of trans guys in real life. And about all I can tell you is that your mileage may vary. I know one guy who started T three years ago and still battles serious acne on his face and body, and I have another friend who seems to be like me; he gets a zit every now and then, and that's it. Experiences with acne run the gamut, but it seems to be perfectly normal to have acne for a few years. See what the other guys say, though.