I personally wait until at least 2-3 months old, then it's healthy snacks like fresh alfalfa sprouts, fruit, oats, grass, weeds, worms, sunflower seeds, ect... Make sure they have access to grit to break down the different foods.
You should give them more of a nutritional kind of snack. You can try yogurt and oatmeal, make sure you give baby grit too. I use meal worms for my more flighty chicks. A momma hen will have her babies foraging within a week after hatching. Get the mealworms loads of fun.
Michele