It depends on how much you have been smoking, and for how long. It also depends on how much body fat you have, and how much you anticipate losing in the next two weeks.

You're going to want to drink plenty of water, get plenty of exercise (maybe not above you normal training, but at least do that much), and then absolutely quit 5-10 days ahead. If you smoke like... a bowl a week, then five days ought to be enough, but if you smoke like... five bowls a day, you're going to need the whole two weeks to detox.

Also try green tea, lots of fruits and veggies and fiber, and lay off the fast food, try to eat organic foods, they flush toxins from the liver and kidneys faster b/c they don't add to the toxic load of your organs like processed foods.