With a young dragon, you want to be careful not to feed crickets that are too big (no bigger than the space between their eyes). You'll want to offer all he wants to eat within about a 10 minute window, a couple of times each day. I like to feed bugs in small batches of maybe 5 or so at a time so they're easy to track. Just dust a small batch and drop them in. Repeat until he loses interest or 10-15 minutes go by. Remove any leftovers from the enclosure. I'd avoid using mealworms as a treat because they can be difficult for the young ones to digest (and don't provide a whole lot in the way of nutrition). Phoenix Worms would be a better choice because they're softer and are small/easy to eat. His appetite will fluctuate depending on mood (less eating during a shed for example) so don't worry much about the quantity of his meals but rather watch for trends and compare what he's eating to what he has in the past.