Ok here's my baby rescue strategy. Not that he needs to be rescued but here is what I do when I get a rescued baby.
In a small bottle lid (2" dia. ish) offer Repcal juvenile pellets moistened with apple juice.
Offer romaine lettuce. Try feeding by hand. Kinda move it around like you are teasing and they'll take it. Then as they start to take the romaine (beardie favorite) add mustard greens and then others before phasing out romaine.
I'm not a believer in leaving crickets in full time since I think you need to train them to eat when food is available just like in the wild.
Here is a response I wrote to a similar post recently:
I took in a dragon last year that the girl swore was a couple months old. It was 4". I had it 7 weeks and when she took it back it was only 5 1/2". I don't know why some grow very slow even with the best of conditions. The important thing is that it's growing but I would still recheck all of your husbandry specs.
The outcome of the dragon I had was that it reappeared here 2 months later at 8". About a week after being here she started growing an inch a week. She has laid 130 eggs so far this year and is the largest dragon I've ever had.