The trick is. . . Two weeks after your final fitting, a week and a half before your wedding, take a 5 day job working at a pop up store in SoHo during fashion week. The unique location gives you the opportunity to walk between the sub-basement and third floor fitting/stock rooms at least 30 times a day. All this with the added benefit of 15 pounds of clothing while making said trips gives your arms and legs a wonderful workout. You won't have any need to hit the gym. It's a good thing too since you'll be working for 13 hours a day. With 45 minutes for lunch and two 15 minute breaks it's physically impossible for you to consume as many calories as you're burning so you're guaranteed to see see a decrease in size. That way 8 days before your wedding without any time to make reasonable alterations the only wonder you'll have about your bra is "where the heck did my boobs go?"