Please do it. It definitely helps you prepare for when you are out of surgery. I just had mine on Nov 6 still only consuming clear liquids , ice , ice pops , and jello . Avoid anything with sugar it can give you dumping syndrome.
It all depends on the doctors office tbh. Some have days where they specifically work on patient files and insurance submissions. But, once they have informed you of submission wait about a week and contact your provider. Speaking with them sometimes help. I have affinity and received my approval with in two weeks after submission