The majority of prostate cancer is slow-developing, so a few months shouldn't usually matter: as someone else mentioned, if you see a different Gleason score post-op, it's typically because the biopsy needle missed something in the haystack of your prostate.

But there are exceptions. A minority of us have very fast-moving cancer that can escape the prostate rapidly. My metastasised tumour grew so fast that it compressed my spine within a month and left me paraplegic for over a yeae. Typically, you'd be seeing Gleason 8 or 9 with a cancer like that (and even most of them don't spread that quickly).

So most likely, the delay wouldn't matter (especially if the Gleason score in the biopsy was low), but there's always a tiny risk.