As a chameleon grows, its nails will also grow proportionally. I have never seen a normal, healthy chameleon that required periodic nail trims. Chameleons need their sharp nails to hold onto branches when climbing about the habitat. The claws usually wear down through usage. If a toe has been broken, infected or otherwise injured, it may not make proper contact with branches, and it may therefore tend to grow too long. But that should only occur on injured digits.
In birds, overgrown claws (and beaks) can be a sign of liver disease, but I have not seen this as a problem in herps.
I suspect that your chameleon’s nails are probably of normal length, but as always, if you think that the nails are too long, my advice will be to please have your lizard evaluated by a herp vet before trying to cut them yourself. Chameleons really need those nails for holding on, so I would advise not trimming them yourself, at least for the first time, if it is deemed necessary. Claws have a blood supply and if you trimmed them too short, you would cause bleeding, which can be serious in a young chameleon, and may also lead to infection of the nail beds. Also, the stress of the procedure is also a consideration, as chameleons are stressed by handling.