I would wait a while on the scratch bc the pieces are usually on the big side. I usually feed things like boiled eggs, bananas, yogurt, mealworms, crickets- small treats. The bugs require grit, obviously, the soft foods don't but its there regardless. I fill up a small, shallow Tupperware bowl with dirt. They will spend alot of time scratching in the dirt so it tends to get poopy, I just dump it and refill when its dirty (har, har). If your brooder has a wire top, you may want to cover it with an old sheet bc they throw dirt everywhere and the dust they make travels further than you'd think!
Nikki