Just dropped off a bridesmaid dress for a wedding that's on the 23rd. The owner asked when I wanted to pick it up and I asked if the following week (seriously asked for it within 7 day) and she said that it wasn't a problem. Not only can she get it done fast but she doesn't charge an arm and a leg.
The lady who owns the shoppe is sweet and helpful and she's a heck of a lot cheaper than your big name alteration places. I've been to her several times over the past few years and have never been disappointed.