New To This23

I have been waiting over a month to get into the nutritionist. I have an appointment, but I would love any advice on what to do diet-wise to lose weight before surgery. Like most of you, I have also struggled with my weight and have successfully yo-yo dieted myself into the above 300lb range. I feel like eating in a calorie deficit at my weight, it should come off, but it hasn't been and I have been tracking my food too.  Thank you