I went from an 11/12 and am probably now on the 8/9 side of things - I'm fitting into my size 9s quite nicely and I have some size 8 dresses that look good on me, if a bit loose (style of the dress though I think) so it's taken me about 30 pounds or so, and roughly 5 months, to drop 2 dress sizes.
One thing to keep in mind though, is it depends where you lose weight from first, and how quickly you lose weight. I'm taking the slow & winding road for weight loss because I'm not willing to give up my occasional treats like eating slightly unhealthy foods, so I've had gains during my weight loss journey, as well as losses.
