“How soon should you have radiotherapy after surgery?”

It seems strange anyone would ask such a question in this forum.
 
This is a complex decision shared with surgery, medical oncology and Radiation Oncology. Numerous factors including surgery type, incision, cancer type, tumor location, stage, previous radiation, genomics, pre-albumin levels just to mention a few.
 
I would assume you have cancer, and are slated for surgery, and post operative radiation? If so, I would caution you most strongly against an internet chat room second opinion. If you are less than confident with your medical care, get a second opinion. A real second opinion. From a real Oncology team.
 
Good luck.