When the shedding process begins, you are going to notice that the skin is getting "dull" and losing its tones, with the big give away being the salmon colored belly scales. Then wait a couple days and you will notice that the eyes will turn extremely milky, and then the eyes will clear up. After that the snake will physically shed it's skin. The process takes around 10-12 days to complete. Its very possible your snake could be shedding again because baby/younger BP's shed quite often, especially if you have been feeding him properly and he hasn't been refusing.
here is a link to a more in depth description of the process, that can also be found on the sticky tabs on the general BP part of the ball python forum page.
http://ball-pythons.net/forums/showt...edding-Process