proper temperatures are very important for beardies. Measure your basking spot with a digital indoor/outdoor thermometer--about $10 at any store or better yet use a temp gun. The basking spot needs to be at least 100F and most like it around 110F for babies--cool side should be around 75-80F. A 22 gallon should hold him for 4-5 months...I like and use 75 gallon tanks for both of my beardies.
Once he gets settled in he will be eating 25-50 crickets a day. It is usually cheaper to order them in bulk online... when you said you fed him 'lettuce' make sure it is not iceburg as that is bad stuff to use on any regular basis. Staple greens are the dark leafy ones like Mustard, Collard, Kale and Turnip. www.beautifuldragons.com has a great food list and care sheet.
Since you have chams you may want to start a silkworm colony--as they also make a great feeder for beardies too. I do have to purchase the silkworm chow, but they take very little effort and do not smell--plus they are so easy to breed.
Your baby probably had a February hatch date (I'd guess around 6 weeks old)--why not use Valentines Day as his birthday?
Take lots of pictures now as they grow FAST!