I would go with 1-2 weeks before the big day. It's close enough to be exciting, but not so close as to have a potentially adverse affect on the ceremony. Obviously, the night before could be a disaster. Hung over bride, anyone?

I agree with donnaaycock. I know of a few people that had it the night before and erm...well the less said about that the better. So 1-3 weeks before the big day is great. It gives you enough time to enjoy yourself but gives you time to recover (especially if anything gets shaved off or anything like that)...enjoy!