Shine a flashlight down his belly, into the pointed end of the egg, and look for yolk. If no yolk, then he is safe to push out -- I'd still let him push out on his own, when he is ready. But if you still see any unabsorbed yolk, definitely don't pull him out yet. Unabsorbed yolk can easily bust, and you most definitely don't want that to happen. Its safest in the shell.