Nine weeks post op and walked today's Ambleside Parkrun. I was very pleased to finish last in 55:44. I'm been using a walking pole rather than crutches. The starter apologised that the course had been slightly altered to avoid a flooded section and as a result may not be exactly 5k, but about an hour for about 5k will do me well for the moment. I'm not about to try running, but will gradually increase my walking mileage and move on to terrain that's not completely flat.
Incidently the surgeon explained that above a slow walking pace there's less wear on the replacement joint components. This is because the fluid inside the joint better lubricates the surfaces when moving at speed, creating a sort of aquaplaning effect. A few people have expressed disbelief, but it seems to make sense to me.