Took the words right out of my mouth, he looks like he is no older than maybe 2 months or so, so either the person or shop you bought him from didn't really know how old he was, or they lied to you about his age, or he's very stunted. Either way beardies do often suffer from relocation stress when they go to a new home, and this in general lasts for at least a week, sometimes up to 2 weeks or more. They often don't want to be touched, don't eat much, and hide a lot of the time during this period, but he'll come around. Just keep offering live insects and fresh greens.
Never, ever, ever feed your beardie ANYTHING THAT IS FREEZE-DRIED!!! No freeze-dried insects at all, and no freeze-dried, pre-packaged greens or veggies! Freeze-dried insects are just about the worse thing you can feed them, they contain absolutely no nutrition at all and at his size and she he needs 3 LIVE INSECT FEEDINGS EVERY DAY, where he is allowed to eat as many live insects as he wants to eat in a 10-15 minute period. Also, FREEZE-DRIED INSECTS CONTAIN NO MOISTURE AT ALL, AND BEARDIES GET THEIR DAILY
HYDRATION FROM THEIR LIVE INSECTS AND FRESH GREENS! So freeze-dried insects will not only dehydrate him, but they are also A HUGE IMPACTION RISK!!! THERE IS A POST ON HERE RIGHT NOW WHERE A BEARDIE WAS FED FREEZE-DRIED MEALWORMS AND CRICKETS AND BECAME IMMEDIATELY IMPACTED AND STARTED VOMITING!
So one live insect feeding session in the morning (after his UVB tube and his basking light have been turned on for at least an hour before feeding him, IMPORTANT!!!), the second feeding session around noon or in the early afternoon, and the third feeding session in the early evening, at a time where his UVB tube and his basking light will be left on for at least 1-2 hours before bed so he can digest his food.
Proper live, staple, feeder insects that are appropriate for a baby or juvenile beardie that is growing furiously are live crickets, live dubia roaches, live Phoenix Worms/Calciworms/Reptiworms/BSFL (all the same thing, just different brand names), live silkworms, and other species of roaches. Make sure that any insect he eats, especially crickets and roaches that have hard exoskeletons are no larger than the space between his eyes. Mealworms should not be fed to beardies, especially babies or juveniles, because they have very hard outer shells that they cannot digest and they often cause impactions, and they are very low in protein and high in fat. Wax worms are only treats, as again they have little to no nutritional value and are loaded with fat. Maybe give him a few wax worms a week as treats, which you can hand feed him to help bonding.
Your best bet is to order whatever insect you choose as a staple feeder online, in bulk. You'll save a fortune and you don't have to run to a pet shop once or twice a week. Lots of people start their own dubia roach colonies. He'll be eating a ton of live bugs each day, on average a growing baby or juvenile beardie will eat between 40-60 live crickets per day.