Nadine,
It sounds like he is doing really well. I watched a TV programme last week about a much older chap who had a big stroke and his progress over 4 years to return to good mobility and health. I don’t know if it will play overseas but if it does, it may be worth watching to at least understand the stages and the rate of recovery that the patient achieved. I am inclined to think that your son is already making very good progress.
http://www.avmsurvivors.org/t/my-amazing-brain-bbc-horizon/19466
Very best wishes for a full recovery,
Richard