Mine entered EI services at 11mo and from that point on it was insisted that he had to be exposed to "typically developing age-peers"... which we diligently did. We only did full-time for one year but I have to say that by the time he was 4yo, we'd had it. He's been home since then and is now 6-1/2yo. About 6mo ago, his dx was lifted with the caveat that at 8yo he would likely be dx'd with Asperger's.
The preschool "disabled" classroom wasn't a good fit for him and we knew it (and so did the preschool teacher) so we tried a mixed preschool classroom for him. After that, we tried a mainstream school with a very different kind of teaching philosophy. That one was the worst because they really just pigeon-holed our son. Then we went with a small Montessori only to find that he sat in the book nook the entire time he was there.
So he came home and I took him to the school for his therapies. THAT did not go over well with the schools. In their eyes--you're not qualified to deal with your SN child. Period. Now... I'm a licensed teacher with additional graduate credits in SpEd and specifically teaching kids with autism. Didn't matter: they needed the social aspect. EVERY child in the spectrum could only benefit from the social aspect of the classroom.
Well... notsomuch. And I have to say that my son has benefited IMMENSELY by NOT being in the classroom. I'll share why in case it helps anyone:
While at home, my son had 1-on-1 social training. Additionally, that social training was acceptable to his parents and in line with what they found to be socially acceptable because we were the teachers.
My son went everywhere with me and watched me interact with all kinds of people. If he wanted to interact with them, I was right there to supervise and if need be, correct him. When he was on the playground or in a play group, I was able to see--first-hand--what transpired so that I could work through it with him while it was fresh in his mind, based on what ACTUALLY happened vs. what he could remember and/or his teacher could remember (or actually witnessed). If he got his feelings hurt, I could address the "what can we do different" things right then and there. I didn't intervene much, but being able to see what was going on and correct HIS memory of it to get to the heart of matters was a big deal.
I can honestly say that there's no way in heck he'd have had that kind of socialization in a classroom. Not ever. And two years later, I finally feel like he is socialized enough that he COULD be in a classroom now. I don't suspect that would've been the case if he'd attended a classroom program.
Now, admittedly, I'm at home full-time and we are not "stay at home" people... so he did get out and about to get those experiences. And I have a 21mo dd which has intermittently made it a little difficult. But things are good overall. And the district no longer argues with me much.