I waited until after the first week to start excercising. It takes time for your body to adjust to burning fat instead of carbs. I would personally wait, but make sure that as soon as the "energy surge" kicks in that you start excersising on a regular basis. There's no need to torture yourself while your body is still getting used to things.

But after that we're going to kick you in the bum if you don't excersise. LOL.

~Angi~