It's not just whether or not you will be permitted to fly (it is actually quite a short time - 10 days, I think) - the bigger issue is how long before you will be continent enough to travel comfortably, able to walk any distance, stay seated in an upright position for long periods of time, pull a suitcase, etc etc plus the need to keep any scar tissue out of the sun. Then you have to consider how the op may affect you emotionally; many cancer patients cope fine while they are preparing for treatment (adrenaline) but once it is over, can find themselves with very low mood or even depression, which makes a holiday not much fun for anyone. And then there is the matter of travel insurance.
If the surgeon says it is a good idea when you see him/her, then yes I would suggest you give it serious consideration.