Ive been told this in the past:
New hatchlings go in 6-15 quarts. If it seems bigger than appropriate, you can always provide enough ground cover to make your bp feel more secure. Once they hit 400-500 grams I would switch them into 28-32 quart tubs. The males will stay in these tubs for the remainder of their lives. The females will move into 41 quart or CB70's when they get over 1000-1200 grams. Other people might do it slightly different.
Congrats on making the switch!