At his age the priority is keeping up the supply of high quality live insects & dietary calcium. His diet should be = insects , as many as he wants twice per day , greens and veg daily if he nibbles on them - some will nibble on the sly as they are shy of being people watching them eat.
I found it was helpful to weigh the greens & grated veg before the hatchling / juvenile gets it, and again after the dragon has gone to sleep , the difference is a combination of drying & and what's been nibbled.
The loss in weight by drying is easy assessed by doing a simple experiment of leaving some out for the day and weighing it before and after.
Offer him greens and grated / finely diced veg daily but if he shows no interest in them don't obsess over it .
Simply give the uneaten veg and greens to the crickets / locusts / roaches as their gutload/food and source of
hydration. He'll get them in disguise that way and will get the benefits he would have otherwise received anyway.