I would go ahead and find something on the basis that August is a shambles with end of sale stuff and Autumn stuff out. Yet the weather might be quite hot and its frustrating when everything is out of stock.
Makes me wonder if I should get something for my sister-in-law's wedding in September...I might wait a bit. Hmmm.
Yes I think you should go ahead - perhaps get something that's a little on the 'snug' side to allow for the weight loss! Monsoon are usually quite good for longer length dresses.As is whitestuff for something a little more smart/casual