It just takes time for them to get used to you. Juveniles can be pretty nippy as someone stated above. I mean like most animals they have no idea what these giant pink things(your hands) are doing when they wrap around their body. Their first move is to protect themselves the only way they know how: striking at the thing that scares them.
Pick him up from towards the back. Just move slow. If he bites you and you put him back he's only going to catch on that biting will make you leave. That's a cycle you don't want to get started.
Good luck and just take it slow!