Hi,
If it were me, I'd already be in the Animal hospital. However, I don't know what part of the country you are in, so it may not be feasable.
Until you can get the dog to the vets, perhaps you should put back on the lampshade thing you got at the time of the operation, just to stop it being at the wound and making it worse. Also, if you have any antiseptic ointment that you would have also got at the time, still left, you could put this on it also, just to keep it from getting infected until such time as your vet is back to work on Monday.
Hope it works out ok.