Personally I would always recommend shaving before you go to any formal do - It makes a better impression, and TBH women prefer clean shaven men, as then dont get a "Beard Rash".
I once asked a female friend why she didn't like unshaven men, and she said it was because she felt the beard was hiding something..
If you have the time and the cash, go to a barbers and get a "proper" shave - with hot towels and a "cut-throat" razor - I get one every so often, and it is the bet shave you can get, with the bonus of having an attractive women (if you are lucky) paying attention to you and making sure you don't have any stubble left over
