try to be in the best shape you can.

generally, the better contour you can get on your chest, the easier it is for the surgeon to place your scars well and get the contouring right.
the thinner you are, the less likely it will be that you'll have dog ears. (if youre having DI)
as for the wait? sorry.

it just sucks. just think.. you'll have the best christmas present to yourself EVER.