I had symptoms of prostate problems, but shrugged them off as symptoms of BPH, which may have been true, since my prostate was very enlarged. The symptoms included urinary frequency, and esp. urinary urgency. When I had to go, there darned well better be a toilet or a bush nearby, because I simply couldn't control the urge. Whether those symptoms were in anyway associated with the cancer, I can't say, but they led to the PSA testing, which led to the DRE, which led to the biopsy, and so on.
Your doctor's plan sounds like a good one to me. Rule out prostatitis first.