For the socket, I believe it takes 3 to 6 months before the bone is fully grown onto the implant. I believe the femoral bone is something that continually remodels, since it is alive. I believe that it is weaker initially after surgery, but strengthens with gradual activity, to the point that it is probably strong enough for impact activity at 6 months.
The evidence from a DEXA study on BHR patients published from Japan is that the bone density in the proximal femur returns to normal 1 year after operation. The at-risk period for femoral neck fracture following the BHR is in the 6 months after surgery. I advise patients not to return to impact sport for 1 year after surgery. For those patients who want to road run, I get them running on a treadmill at 10 months post-op and they resume road running at 12 months post-op. My unit published on activity level after resurfacing some years ago in a group of patients who followed those rules. In young men with a single osteoarthritic hip resurfaced, 92 % played sport and 62 % played impact sport. The ladies were not quite as active, but you can see from the publication that they still had an impressive activity level. In the total group their 10 year implant survival is 99.8 % showing that high activity introduced at a sensible time does not deteriorate the results.
The bone is well healed at 6-12 weeks. I allow running at 6 months. I do not use cementless resurfacing. I use Smith and Nephew Birmingham hip.