I started giving ours grit at about 2 weeks old...sprinkle it on food to start, then gave it to them in a bowl, I freaked out because their crops were HUGE!!! thought they were impacted! everyone here reassured me they were fine and they were!! I use construction sand, it is cheap not too fine and not treated and NO calcium!
They get treats...apples, frozen cherries, rice, flaxseed, wheat germ, steel cut oats and yogurt!
They eat out of my hand a LOT even when I put my hand in with no treats they come running to my hand. Have fun!!