They'll shed when they need to and the rate at which they shed slows as they get bigger. Hatchlings I'd normally expect to shed once every 4-6 weeks and adults 3-5 times a year. However, this can vary wildly between individuals. 8 weeks for a hatchling wouldn't be unknown.
Basically, unless you have symptoms of a completely stuck shed, then there are two possible scenarios:
1) He's not growing as fast as you think and he doesn't need to shed.
2) He's shed and managed to sneak it under the radar somehow. Sometimes the shed skin ends up in a ball (a very small one, with hatchlings) rather than being stretched out. If you don't spot this in the substrate, you can easily spot clean it away without noticing.
Either way, there's nothing you can do about it. He'll shed when he needs to and you can't speed the process up. If he's eating and pooping normally and his skin looks normal, then he's fine.
