Hi T! I don't have any experience of this, but just wanted you to know that I hope you do get some help for him. Getting the dx will open up so many avenues for help for him. I think how long it takes depends on where you are and the Doctors you see. I know some people in real life who have gotten a dx quite quickly and sometimes it can take a bit longer mainly because of waiting times between appointments. Good luck, and I hope it's not too long