Here's my perspective on waiting a year--if insurance, finances, work and family logistics permit, don't wait that long. This is just my perspective, but consider. Your new knee will very shortly, if it hasn't already, taken charge and it will be doing more and more compensating for your unrepaired knee. Give it a year and it will be set in its ways, and then have a small hissy fit when the next knee is done. I am having soft tissue issues with my first knee, which was happy as a lark until my second knee and leg got straightened out and asserted itself.
Mr Jeano wanted me to wait a year between knees because he likes to save up his leave for the fall, our prettiest time of the year. I would've done it 2 months after the first (OS's preference. Me, I would have happily done bilateral.) After a few months I had had it with having one good knee getting better, and one awful knee rapidly getting even more awful. I couldn't enjoy my new good knee!
I overrode Mr Jeano and scheduled the second knee for 6 months after the first, then broke my ankle the day before. So my poor left knee ended up getting its head messed with on several different levels due to having to share the load, then compensate, then being on the only weight bearing leg, then compensating AGAIN, this time for a wonky ankle and even worse knee, and now its in some kind of a power struggle with the new knee, which thinks its The Man. I have to think they would've gotten along better if they were closer in age.