that pushes the old skin from the new skin. How long this takes is controlled by the snake and its interaction with the environment. There are dozens of factors that may cause a shed to speed up or slow down. Some of them are, the health of the snake, the presence of mites, the humidity of the cage, how well hydrated the snake is, the temperature, how rapidly the snake is growing, the age of the snake, etc. As long as your snake is healthy the timing of the shed isn't as important as the quality of the shed. As long as the shed comes off in one piece or mostly one piece, and the eye caps come off then you shouldn't worry about the timing.
David