It usually depends on several factors. But since he/she is growing, I'd say ALOT! My Veileds eat anywhere from 10 to 20+ crickets a day. I think I read somewhere that Adults should eat every other day. Can someone confirm this?
Yeah juvies do eat tremendously, and what you said(10-20 small criquets) sounds right. I usually only feed them dusted criquets those first few months with the ocasionnal small silkie or super worm. As they grow older they will eat less and sometimes every other day. I just stared feeding him every other days(hes a year old panther) I think I just wanted him to eat too much...
I just give my chameleon bigger meals, like the biggest hornworms or silkworms I can find and he ll be ok for the rest of the day...I read that some of these adult hornworms or silkworms equal about a meal of 20+ criquets so no wonder theyre ok for a while after that. Just remember to vary his food and to gut load it.
I have found with my baby and juvie chams, they are gluttons! Babies and juvies will go for anything I put in their cages, 24-7!. But the older they get, the lazier they get. I've found if I feed my adult chams every day, I end up removing crix, worms, mantids, moths at the end of their day-night cycle.
For that reason, I have resorted to feeding my adults every other day...and I hold their "treats", the silkies, wax, supers, horns and moths, to every 3-5 days, depending on their mood. Cham keeping isn't a science...read your creature, follow the basic rules and keep 'em hydrated and happy!