that varies depending on irradiation location/volume and individuals....
Having said this, you should get something comming back within a few weeks to a month after the end of the rad/TX. It seems to be very variable as to what comes back first. (for me it was vanilla, chocolate, later on shrimp (of all things)). It takes many months.. up to a year to reach the new equilibrium. It has been nearly 3 months since the end of the treatment for me and quite a few things have recovered, although some tastes fade very quickly and a good steak is still a waste of money....

Markus