I had ACL reconstruction at 37 years old, Pt very important, I used the stationary bike a lot and was back at work fairly quickly (one month) but i wished I had stretched and got a better range of motion earlier. Its still limited ten years later.
I had a slalom at 3 months, but that didnt feel right and is a vulnerable time, at 4 months though with a Cti brace I was back on the ski and going to tournaments. Six months should be plenty of time. I also enjoyed the recovery period and have trained better/more consistently ever since.