While 2 scoops of icecream 3 days before surgery won't cancel your surgery, you definitely don't want to do that again. Your stomach need to not have the solids in it, especially this close to surgery, because of the anesthesia. If you have food in your system, it can cause dangerous problems for the surgery.
You also want to think about low to no sugar icecream for after the surgery. I don't eat sugar and I am still able to have it. I get Rebel icecream from WalMart. Very low to no sugar, lactose free, very low to no carbs, low calories, absolutely delicious. My favorite flavors are coffee chip, butter pecan, and orange cream. My husband's are birthday cake, triple chocolate, and cherry something (I can't remember the name). They have other flavors, too.
One thing you want to remember, and this really helps me stick to my diet, is there are delicious, healthy, compliant alternatives to the things we love. Icecream, bread, bagels, pizza, cinnamon buns, chicken nuggets, etc... There are ways to make good choices, but you have to want to make them. Being compliant, particularly post surgery, is so so important. WalMart, SafeWay, and Kroger brand stores (Krogers, Fry's, King Soopers, etc) have them. Look for Real Good Foods, Legendary foods, and Atkins.