people here can only tell you what they do or think is right.
The only person that knows his chameleon amd it's appetite is you.
I would not worry to much about feeding to little since chameleons in nature go days if not weeks without food if needed... In captivity it's easier to overfeed them and honestly none of my reptiles ever ate or killed anything if they were not hungry.
So basically it's your job to provide food that has sufficient variety and is properly gut loaded. There's many feeders suitable as a staple, for example crickets and dubia, but one of the both along with silkworms will make a good staple diet too.
If you see a lot of feeders left at the end of the day(or day after if you feed every other day), feed less. If he finishes all every time you may want to give a bit more.
I feed my 7momth old Panther every day and give him around 5 Dubia since they won't escape the cup, along with that around 5 crickets since they will likely escape and become free range, added to that I feed a treat like a couple of silkworms or superworms.
My jax is a different story, he has a small appetite so he has his own schedule.