It should def come back in time, even if they don’t contact you personally the surgery should be chasing the result. They now take 24-48 hours to come back but because it’s the weekend they just may not contact you. If your covid test doesn’t come back they will just take extra precaution during the op (treat you as a patient with covid) it shouldn’t stop your op! But chances of this having to happen are very small. Don’t stress about it!!