I always wait for the first poop .....which usually occurs on the third day. Day 1-3 they are absorbing the egg yolk, and they usually shed, and eat that too. You can offer food, but they don't want to eat.
If you're worried about them being hungry it never hurts to leave a few mealworms in a bowl in their container. They'll hunt for them when they get hungry Most babies hatch with some yolk in their belly and they just aren't hungry until they absorb it, shed and eat their shed and poop it out. Feeding before this is usually just a waste of time and if the insects you're feeding get out they can stress the baby.
My hatchling is on Day 5 now and I can still see the dark shadow of stomach contents....so I am not suprised that my little "Star" didn't seem interested in the pinhead cricket I dropped in for 10 minutes.