I would start him on small size hides (no BP will fit in the minis) then eventually move him up to the mediums.
What I do is start mine in 1/2 of an AP T8 (a full T8 measures 4 x 2 x 1 foot so half is 2 x 2 x 1)
Then when they are big enough I pull the divider out of the cage and let them have the full 4 x 2 x 1 cage.
I feed my young BP's every 4 days, and older BP's every 8 days.