Usually once their nose peeks out, at least the head will come out quite soon after that, but sometimes they take a break at that point and rest with just their head out for up to a day or so. Don't worry, it doesn't mean he's stuck or anything. He'll come the rest of the way out when he is ready. I'm not sure if they are finishing absorbing their yolk, are just really tired from getting that far, or are being lazy. lol. Other times they'll just come right out all at once.