well to be honest, im new to chameleons but! i bought mine from theveiledchameleon.com and he is about 3" and it said he was about 3 and a half months, so id guess around there?
and today my little dude ate about 8 crickets, ive read up to 15? i would say about 10 a day mmaybe?
and for the dripper, what i did was set it up so its dripping onto the leaves of the enclosure so it kind of cascades down the leaves, that would probably be the best way to do it, and if he gets thirsty he will go get some! also, dont forget to mist him 3-4 times a day for about 2 or 3 mins each misting or make sure that the leaves are decently wet so the litttle guy has options!
All chams grow at different rates, it's possible he could be anywhere from 3-4 months old depending on how that cham personally grows. For a young cham you should be feeding anywhere between 15-20 crickets that are about 3 weeks old depending on its size. The rule of thumb is nothing bigger then the width in between yours chams eyes. For treats you can use meal worms but not many as they're pretty much junk food. Once your chams older then you can introduce other feeders as well. If you find roaches small enough and silk worms, you can feed those as well. As an adult you can feed every other day.
Don't forgot you'll have to have a dusting schedule as well.
You should still have a dripper, just because you don't see your cham drink from the dripper doesn't mean he isn't. Of course, mist 3-4 times a day to keep up humidity and have real plants as veileds do enjoy some veggies.
It could be 3+months , chams grow at diffrent rates depending on there enviroment, as far as feeding goes. offer 15 well gut loaded crickets, and remove any that are left before your lights go out.and make sure your supplmenting well while your little guy is growing!!!This is the best site on the web to research and learn about chameleon care.