Hatchlings can go 6 or 7 weeks before eating. I had one hatch on July 23 this year. No interest in food. The others ate fine, but this one wanted nothing to do with food. Finally ate on Sept 7 (46 days, almost 7 weeks).
If there's a medical condition or problem that's one thing, but an otherwise healthy hatchling can make it to week 6 or 7 before you need to start considering alternatives.