Could you just go to the wedding ceremony and beg off from the reception (headache, sick, whatever)? This would be a really slippery situation that I wouldn't have wanted to be in with only days under my belt.
It really does take a bit of time to build up your sober muscles. This sounds like going straight for the 200 pound barbell before you have lifted 5 pounds.
The thing with going sober is that there will always be some event or celebration coming down the pipeline that will test us. We need to have time to prepare for the test.
I hope you decide to start with easier challenges first
