Yeah, I know but brugs grow so fast . . . I had one - my first start of Monster White - go from a cutting size to a 4ft. shrub in one season. Three times I re-potted it. The heck with that, let the thing grow!
My belief is the bigger pot you put it in the bigger it will get by the fall. If you want to hold them back to a certain size, that's the only good reason to use smaller pots.
That being said, my huge ones are now in the biggest pots that I can handle, so I just prune them back after each bloom cycle to keep them going in the same pot. I've yanked them and refreshed the soil once, and I add scoops of new potting soil on top occasionally after I fertilize. I may eventually have to resort to root pruning, but really I think I'll just grow a new plant. The big ones can retire to the back garden, and will slowly decline - they can't compete with all the tree roots around our house.
These pictures show the cuttings started in early May of 2011. The wimpy one on the left is Monster White. The other two pics were taken in September of 2011. Nuff said.