Hi @sistersinhim, from my own experience and the experience of other TKR'd gym goers I've met in recent months, strength/weight exercises started anywhere from 2 weeks to 2 months. Exercises included use of machines like the leg press, leg extension, hamstring curl, abductor/adductor machines. Stronger, more stable legs make a return to "normal" life a lot quicker and safer. Clearly, if one were to engage in such exercises, careful monitoring of its effects on the body is a must.Absolutely not. Weight training should not begin until 3-4 months. Your PT needs to go back for up-to-date training on rehabbing a joint replacement. You don't have a sports injury, you are recovering from a traumatic surgical procedure.
In my case, prior to my RTKR (Dec 2021), I worked hard on strengthening my legs. That allowed me to return to strengthening routines fairly quickly after my RTKR (day 13, starting with the leg press with the minimum machine weight). It took another 2 months to get back to pre-op leg strength. In the case of my left leg - it benefited greatly from the build-up to my RTKR as well as the rehabbing of my right leg - on day 8 post-LTKR I started with the leg press machine, also with the minimum machine weight. By the end of month 1, my left was back to pre-op strength ---- which is not to say it was back to normal --- as it clearly wasn't due to all the healing that was still ongoing.
My OS had no qualms giving me the okay to work my legs hard as soon as I could bear it ... as with my physio. That too seems to be true with most of the other "classmates" I've met (meet) at the gym.
But - again - it is important for one to know one's limitations and rehab accordingly.
All the best.