Andee
Chameleon Enthusiast
Umm considering how small he is currently I would keep him in something smaller than something for a 5 month old. However than can be rectified easily. You have the correct dimensions for most juvenile chameleons, sometimes depending on the species and personality they need to be upgraded quicker. However since he is so small, at the moment just make the cage you a building smaller by partitioning off part of it with something you can easily.remove later on.