Hi Alan, if you think about the practicalities of your surgery, all of your guts have to be moved around out of the way to get at your prostate, and then shoved back in in whatever order, and it takes time for normal peristaltic action to be restored after all that disruption.
I was discharged with Sennakot (a laxative), some kind of fibre husk drink similar to Fibrogel, and laxative suppositories. Fortunately, I didn’t need any of them. The first fart was a positive pleasure (followed by many more), and a bowel movement on day three or four, resulting in great relief.
It is true that analgesic drugs can cause constipation in themselves, so I think if you wait a bit longer, once your bowels have sorted themselves out, you should be OK.
Best of luck with your recovery.