Screening specifically for autism isn't recommended before then, but that seems to because differentiating autism from other development delay or disorder is difficult then; it seems to often manifest detectable signs as early as 2 months, though they are mostly signs that could be associated with other developmental conditions.
> because it takes that long for the brain subsystems involved to be wired up in more or less their final configuration.
> Funnily enough, that's about the same time frame as when the kid receives their first vaccinations.
No, it's not. The first recommended vaccine (HepB first dose) is at birth, and there are a lot before 18 mo., by 18 mo. they are hitting the fourth dose for some vaccines.
https://www.cdc.gov/vaccines/schedules/hcp/imz/child-adolesc...
...and then right after the vaccine they are completely mentally retarded, can't make eye contact, and no longer speak the words they spoke prior to the vaccination.
Funnily enough, that's about the same time frame as when the kid receives their first vaccinations.
To the nonscientific mind, correlation=causation a lot of the time. Add to that the increased difficulty in caring for an autistic child, the belief that autistic people are "soulless" or somehow not capable of empathy, the desire of parents for their children to live a "normal" life, and the significant subset of parents who view their children as lifestyle accessories rather than independent people and so are embarrassed by a child with special needs, and you have enough fear and dread that things might've been different had I made the choice not to vaccinate to kick off a worldwide movement.