My grandpa (68) was diagnosed with a pretty big (at least that's what the docs told me - two of them whom I contacted outside of the hospital told me that a few weeks more and it could have become inoperable) grade 4 glioblastoma two weeks ago. 10 days ago he had the surgery - overall, everything looks good so far (slight hemiparesis remained but I'm still counting on parts of it resolving over time + it's still nothing compared to the magnitude of the whole thing), the docs are happy and all. 

Simultaneously, the hospital told us to start looking for radiotherapy cause the sooner you start the therapy, the better. I read the same on the internet. The problem is, I have a hard time of wrapping my head around "the sooner the better" as a layman and we're all growing a little paranoid with my family cause it's not exactly a turbo-quick thing in my country anyway but now with covid, it's considerably harder. So far, our research and asking around seem to indicate that usually, it takes around a week to get an appointment with an oncologist after you get your histopathology results (cause nobody wants to even see you without it) of the tumor and then as long as a month to actually start the radiations. 

How does that go along with the "let's start it ASAP" recommendation? Is it too long and I should look in cities much further away to have a shot of moving it a week or so back? Or is a month totally fine? I just don't know what "fast" means in this context - does that mean "let's just do it in the first possible open date they give you" or "try to start it literally a week after being released from the hospital or else every day of delay is going to make the therapy harder"? I guess the question is just, is there a window of time within which it makes no difference whether you start the therapy 5, 10 or 15 days this way or another or is there no such window and literally every day counts here?