Jack,
First off, good luck with the surgery.
Secondly, I'm almost pleased that you tested positive with very mild symptoms. Make a strong recovery and you should have antibodies protecting you until a vaccine becomes available.
It is possible to my knowledge that after 14 days you could still be positive, but less likely given your mild symptoms. Did they give you any medications such as remdesivir cocktail with antibodies that has shown to hasten recovery?
For any medical procedure, you have to be tested two or 3 days before. I had to before a routine colonoscopy. I am guessing they will wait to retest you for Covid a couple of days before surgery because it makes no sense to do otherwise due to presurgical protocols.
Good luck and prayers for a great outcome and speedy recovery. You are a great Alum, and my most reliable baseball expert on redmen.com.