To give a ballpark, I've had a birdsnest that was about a 1.5" cube, and after about 8 months it was the size of a baseball. At the same time, I got an Acro about 2" tall. After the same 8 months, Its branches have not grown at all, only somewhat encrusted on the rock.
I've had certain colors of zoas go from 3 polyps to a hundred in about a year, and also had some that went from 3 to 7 in a year. It can very ALOT which is why you have a hard time getting an answer. It's hard to even give a ballpark answer. I base my lighting off of coral color, and nutrients off of algea growth (and of course testing). I keep nitrates and phosphates low enough that I only have to clean the glass every 3-4 days, and I keep lighting bright, but not so bright that the corals look like they are getting pale. Whatever you do, only make small changes at a time and try not to stress about it too much.