I am also doing weight watchers (we have a thread to help each other) I've lost 9 lbs. so far, I want to lose as much as I can before I order my dress, but I want to continue to lose right up until the day I leave for mexico!!
I also looked for dresses with corset backs, so that it will eliminate the need to have alterations more than once. I'm going to wait as long as I can to order it and I am also going to wait until the last possible minute to get it altered.
I do 30 minutes of jogging/walking on the treadmill, I aim for everyday, but usually it ends up being 3-4 times a week, which I need to work on! But I really need to get myself back into the habit of doing weights too, at least a couple times a week.