It would depend on how little he was when you got him. A tiny baby would get literally lost in a tank that size...and would not be able to find his crickets very well...which they need as a staple of their diet. A 15 or 20 gal is good for a small baby to a medium juvie.
I would highly recommend starting out with a juvie...one about 8-12 months old. By then, they are already experienced "hunters" and are also beginning to transition over to veggies and fruits, which makes them a lot easier to care for. And if you got one that size, you could put him in the big tank right off. But that's a matter of personal choice. I'm glad I didn't get a tiny baby, even though they are CUTE! :)