There's much more than crickets out there! Locusts, a few species of cockroaches, mealworms, calci-worms, butter worms, silk worms (and more!). A young beardy should get as much variety as possible to prevent excesses and deficiencies.
Veg wise, offer it but don't worry if they don't take to it at this young age. This is a good link > Untitled Document
< again variety is really important. Try not to offer foods that are moderate/high in oxalates and goitrogens too frequently though.