I am a former j-poucher who was shocked post surgery by the many ways having a j pouch could be worse than an ileostomy or life with a wonky colon. So first, I would recommend googling something along the lines of “j pouch failure rate” or the like and making sure you are prepared. There are a lot of stats thrown around, but the latest numbers from docs I trust who see both the good and the bad is that around 50% have complications (some minor, some major) and 20% are removed (for varying reasons.) Knowing what to look for if you should have an issue (pouchitis, cuffitis, fissure, abscess, blockage, etc.) will help you deal with it better or quicker.
Then, given your 3–year hiatus from using your rectum, I’d google “pelvic floor physical therapy” or “pelvic PT” and consider tacking on “men” so you don’t have to wade through all the info that pertains to women post-partem. Be prepared for the difficulty you might have with physically retaining your new stool consistency with lax rectal muscles. Understand a lot of j-pouchers have to alter their diet to manage retention issues and be prepared to deal with this as well. Alas, I was not.
Lastly, I would recommend googling “continent ileostomy.” This is what I have now after having had so many problems I had to have my j pouch removed after 5 miserable years. I didn’t even know it was an option and wish I had been made aware earlier. (Many thanks to the others on this site who had to go this route and provided so much valuable info and support!)
I know most people have good results, so I write this not to dissuade, but because I just wish I had been more prepared for what else was possible. I second other recommendations to be prepared for how you are going to handle leakage (pads?) and have a bidet seat installed. And buy some Balneol and Calmoseptine to have on hand in the hospital and at home, very helpful stuff for dealing with the inevitable butt burn. I’m absolutely serious about the bidet, as in, I can’t believe I wasn’t given a script for one prior to surgery, it’s that important.
Best of luck & God bless!