While this is a very serious diagnosis, I think it won't make a huge difference to wait an extra week on the surgery.
My tumor sat in my tonsil for TWO YEARS before my ENT thought maybe I should have a tonsillectomy. That was a surprise for the surgeon. After surgery I waited 6 weeks before beginning treatment. Take a deep breath and try(I know it's hard) to keep calm, while gathering all the info you can on treatments. Get a notebook and write down all your questions for the doctor. Best of luck to you!!