L.P.
I agree with all of the other comments that it will depend on the child, and that the food intake may vary from day to day.
My DD is in daycare, and they mimic what the other mom's below said. Breakfast, snack, lunch, snack, dinner. It doen't need to be big, some cherrios or cheese. See if he wants it.
I would also check with your Pediatrician and see what they have to say about it.
Good luck.