Well, I watched my husband drinking from day one of my sobriety. That is, however, a little different than going into a party situation, where you know there will be pressure to drink.
I didn't go to my first party with alcohol until I had been sober almost a year. We don't have those kinds of friends, and it just never came up. I have no clue what I would have done had we a big social circle that liked to have drinking parties. I think it would have been a lot harder for me to stay sober, though.
Edited to add: If you really want to stay sober, develop some dread (and fake) illness right before the trip and bow out. I'm not saying you can't practice self-control, but it's sure going to be hard.