Welcome! Ball python size varies pretty widely, but at about two feet long a reasonable guess would be that he's a late 2003 hatchling. As the others said, it would be a good idea to start feeding him on a weekly basis, one rat pup or a large mouse ought to do it. Have you been feeding live? If so, it would be a good idea to switch him over to eating pre-killed or frozen/thawed prey, especially as you increase the prey size. Live prey can do a lot of damage to a snake, and I'm sure you want to keep him safe.