One of my observations is that those who First take care of their physical fitness do the best with their surgery. The other is that attitude is very important. People who either are or become physically fit have already demonstrated their willingness to do what is necessary for rehab and to make the replacement last. It isn't a matter of doing it now, or doing it later. It is a matter of having the physical fitness and attitude to make it a success.

When to do the procedure depends on when the two keys are taken care of.

I know this doesn't directly answer the question. But, the result of getting ready for the procedure will produce the answers.

Lastly, find someone you trust who can be your advocate.