Contact lenses may change the shape of your cornea and make your doctor recommend PRK/LASEK rather than LASIK. In some cases, they may recommend no surgery at all based on the shape appearance.
Your contact lenses may affect your prescription by pressing on your eye. This is usually minimal, especially with soft lenses. Assuming this is the case, the worst thing that can happen is a slight increase in your chance of a touch-up. There is no evidence that something bad will happen.
We usually recommend for my patients to stay out of their soft lenses for 2 weeks because it is an FDA recommendation. I recommend at least 4-6 weeks if you wear RGP/hard lenses because they tend to have a more long-lasting effect on the shape of the eye.