Most of us feed babies a large handful. Then if they eat all of that, we give them a larger handful the next time. I own a leopard and when he was little and still today, he is now two, I always make sure he has food left over. Just incase he gets the munchies. Don't forget, they are used to grazing thought out the day. They will eat what the need.
If you don't have a good size yard with lots of grass they will eat you broke. Even with a big yard you still have to feed them other things as adults though. A large adult like mine can eat a half acre of grass all the way down to the dirt in a summer if other food is not given.
I've never seen my 1 year old sulcata stop eating. He will stop, do some laps and then eat more. It's amazing. He is 6 inches and wil eat 3x the amount of his shell 2-3 times a day.
Grazing on grass and weeds outdoors is best. They will graze and walk all day and never seem to fill up.
Indoors I give hatchlings as much as they will eat and always have food available. I adjust the intake for older ones and give them as much as I anticipate they will eat in a day.