Not sure how our surgeon outlines his pre-op but plan on starting your diet now. Why wait, remember the band is not a quick fix, nor does it stop what you put in your mouth. I started my diet the day first day I went to my surgeon, he said I had to lose 15 pounds to have the surgery. (His requirement is that all of his patience lose weight pre-op). I have lost 50 pounds so far, my paperwork just went to the insurance for approval so I will find out in the next few weeks, if I have approval. But the point to this is start now, limit the calories and fat you eat so that once you have the band you won't crave these foods as much.
Good Luck