Hi DD8,
Welcome to the group. You're going to get various responses from the group, however I feel that it's the general consensus that getting oneself in condition prior to the surgery truly helps in your post-operative recovery. I too was a bilateral patient (surgeries were approximately 2.5 years ago with Dr. Gross). It was recommended by several members here to try and get yourself in the best shape possible (within reason) before my surgery date.
So I never stopped going to the gym and focused on my legs, glutes (squats, lunges) as well as my upper body. It was helpful to have strength in your arms, back, and chest in the weeks following surgery as you'll of course have limited use of your lower extremities. So in addition to the gym, I never completely stopped trying to play the sports I always enjoyed, though this became increasingly harder to do as the arthritis continued to worsen.
So of course my experience and beliefs are subjective and anecdotal, but I really believed I benefited from the time I put in before the hip resurfacing surgeries. If I recall correctly, I was walking unassisted about 10 days post-surgery. Would I have had a similar outcome if I were to have simply coasted, and done nothing? Perhaps. There are so many personal factors involved in each of our recoveries.
Regardless, my advice is to focus on your glutes (those are the muscles that are impacted the most) and try and keep as fit as reasonably possible and it will pay dividends.
Good luck and keep us informed!
Joe