Hey Mike, I'm a bilat too, and the ROM came back eventually, but it did take a while. I started with some extremely light stretching exercises about three to four weeks after the surgery, it was supervised by the PT, and it was extremely light - no resistance, just moving the leg up as far up as I could.
I started doing the actual stretching about six weeks after the surgery, using a band to bring my leg up straight as I could (again, no real resistance but to move the leg as much as possible). Eventually, at four months or so I started putting some resistance, and my ROM got better.
A couple of things - I did martial arts for 35 years, so I had very good ROM before the OA. Everything I did was under supervision of people experienced with THRs, so they were extremely conservative with any stretching.
It'll come, Mike, but the important thing is to be conservative and let the body heal, and if you do stretch, try to get a professional, preferably one with experience at least with THR to help you. I think for most people, after 6 months is good.