Hi Mindi, you've heard some good advice - first and foremost it's up to you when you decide to have this procedure.
You've already reached that decision, but like the rest of us, as the date approaches you're nervous about it; that's normal, and like Mac mentions, some have cancelled to have it later, when it became clear that it was necessary.
I think I can say that none of us would have had this if there were any other way to improve our OA, but there isn't; that's one thing I can tell you with certainty. I tried everything I could think of to avoid it, from ignoring it (I can tough this out), to physical therapy, massage, change in diet, even a fitness boot camp (fun with OA).
I was also very active, when the OA began, I was doing martial arts classes three times per week, playing basketball twice per week, soccer twice a week and weights three times a week. I was also in leagues for soccer and basketball and doing full contact fighting. All of that incrementally went away, the soccer last when my left hip (the worst one, I did both) started dislocating first as I played, then randomly throughout the day.
Like several here, I felt I waited too long. I could have done it earlier and been back to my old activities (to some degree at least) by now. I feel like I'm in the middle of my recuperation now, can do a lot of my activities, but I really believe I've got another year before my body is back to where I'd like it to be. My advice is that if you know you're going to do it, to go ahead; there is no guarantee, but you have done the best to position yourself for success - the doctor you've chosen is one of the best and the procedure you've chosen (HR) has a very high success rate.
You do need to consider the window of opportunity for having a good HR, but in the end it is your choice, one which everyone respects.