You will see your snake darken, then 2 days after that your snakes eyes will turn blue, then 2-3 days after that your snake will shed, but this is only a aprozamation (sp?). As long as its humide in the tank. He will shed fine. If his skin comes off in little pieces, Just sock him in luke-warm water and then with a damp cloth rub the skin off softly.
Good Luck
Alex