Broadly speaking, there seem to be two schools of thought on this. One is that you continue the AS until there is evidence that the cancer is progressing (I'm assuming that you are Gleason 3+3).
I was on AS from 2014, but an MRI scan in June 2021 showed an area of concern and a biopsy in November moved me from Gleason 3+3 to 3+4 at which point my consultant advised action and I am due to have surgery (RALP) in March. It seemed to be the case with my consultant that once grade 4 was involved he advised action.
The other school is that the cancer is never going to get any better, so you should have it treated while you are relatively young and without giving it the chance to progress to the next stage. If you leave it until you are older then recovery will be slower and beyond a certain age (75?) you may not be considered a suitable case for some treatments.
What course of action you take depends on your particular circumstances, so it's good that you are seeing your consultant in a few weeks and are looking to be informed and ask relevant questions.