Good luck with everything. In my experience, the sooner you can get them evaluated, the better. My nephew is five and a half and was diagnosed last year with Autism. They still haven't pinpointed where he is on the spectrum other than he's fairly high-functioning in most areas (although he really doesn't talk much). I started to worry about him before he turned three. All of a sudden he wasn't making any eye contact and/or trying to communicate. But my little sister (lives with my mom) let my mom dictate getting any evaluation, so it was delayed and probably lost a lot of valuable time. He's now in speech therapy and occupational therapy, so we can see a bit of improvement, but I think the environment he lives in is kind of hampering improvement on a bigger scale. :/
My grandson is four and started having epic meltdowns about six months ago. He also doesn't seem to listen or be able to pay attention to anything he's not interested in for any length of time. He'll dash out in traffic or do other crazy things because he is just so self-driven. He doesn't sleep well and is constantly on the go/never wears down. We were worried about all of it, so we took him in for a checkup and asked the doctor. He has now been diagnosed with ADHD. We asked about whether or not he might be on the spectrum, but the therapist said she doesn't see it because he's so extremely social.
No matter what, be sure to tell the parents to be strong advocates for him and to speak up and be sure the families needs are being met. I think with waiting lists and other crazy things, sometimes the healthcare systems can bog people down and they don't push forward because they don't know what else to do, but have them find local groups that can give them information or resources so they can make informed decisions about care and whatnot. We just stared therapy for Kennedy, and are already thinking we might have to change because the woman doesn't seem to know much more than to go with what almost feels like a scripted format. We asked about a book for helping figure out what to do with the ADHD stuff, and she didn't really have one. To me, that isn't a good sign.
And I don't know if it would help, but I think Ali Edwards' blog has a lot of good information and some resources about Autism because her son, Simon, has it. She's so down-to-earth and wonderful, it helped to read about things from her perspective.
Hugs to you guys.