I am VERY bad at age-guessing... but he sounds like he's over the 4, maybe even 6 month mark. Yuki is roughly 4", maybe a bit more(I haven't exactly measured her) and likely 6-7 months old. So I'm going to GUESS he's 4-6 months old, as he is male, and they're usually bigger than females. I would seek the opinion of someone more experienced though, as this is completely guesswork and comparison with the only veiled I've ever owned...
Feeding is best done at the first half of the day, ideally shortly after the lights go on to give him enough time to digest his food before sleeping. I leave for work shortly after 7, and the lights go on at 6... so I end up feeding my chams at roughly 7 every other day.
Age is a determining factor in how much you should feed your cham too. Since yours is male, it isn't AS important as if he were a female (less eggs = less feeding) but you obviously don't want him to get fat. If he's around 4 months, 10-15(?) appropriate sized feeders a day would be good, until he's around 6(?) months old. After that, feeding roughly the same amount every other day would give him the food he needs and prevent him from going overweight. Of course, each chameleon is different, so you might have to experiment yourself!
Do you only have crickets for your little friend? If yo, I would recommend getting some more feeders! He will thank you in more ways than one with a varied diet. Some good feeder choices are: Phoenix Worms, Silkworms, Horn worms, grasshoppers/locusts(The former are probably better though, I use these because I can only get 1 out of 3...), roaches and BB Flies. Treats (one every couple of weeks) could be mealworms, superworms, butterworms or waxworms... again, only a couple a month at most, they are more fattening than anything. Some fruits and veggies, if he wants them, are also nice for a fresh variety

Yuki starts eating er plants if she doesn't get enough fruits/veggies...
Hopefully this helped a BIT. I'm not 100% certain on age-to-feeder ratios, but hopefully it helps a bit!
