Do you know if your surgeon requires a one week or a two-week liquid diet?
I don't think you're doing it for "no reason". The fact that you're willing to jumpstart the process shows how serious and committed you are. You'd be surprised by how many people aren't as motivated as you are. That's a good sign that you are going to be a big success story!
My surgery was tentatively scheduled before I was approved, too. Insurance companies often say they take weeks to approve you, but often the turnaround is much, much quicker. It only makes sense for them to be conservative with their approval timeframe. At times, there may actually be a backlog of paperwork awaiting evaluation.
My paperwork was sent in on a Friday, and I was approved on Tuesday of the following week. The doctor's insurance person/staff tends to know which carriers take longer and which don't. I have UnitedHealthCare, PPO.
I think it's great that your doctor's office got you locked into for that date. How disappointed you would have been if they had required approval first. What if the approval had been received in time, but your surgery date had been given to someone else. On my surgery date, my surgeon had two other patients. I was number three in his queue.
Ask if you'll be his/her number 1, 2, 3, etc. The smaller the number, the earlier you have to show up for surgery. The first two cases ahead of me turned out to be complicated cases. I was tentatively scheduled for 12:30pm, but ended up on the table at 5pm. I was slightly disappointed, until I asked myself, "Hey, would you want Dr. S to rush his surgery with you just because someone else was anxious for their surgery to begin?" My answer was, "No."