DS was diagnosed shortly before his 9th birthday by the Consultant Community Paediatrician. The GP referred us 14 months earlier. By this point we had gone through a QB test which showed a very strong perfectionist pattern, we had evidence from home and school about his strengths and difficulties plus history of his SALT interventions when he was 3-6. Really she should have taken it on to Psychology, but felt that there was sufficient evidence (including her own subtle observations about his following of instructions, way he followed the conversation and ways of deploying eye contact) to bypass that stage and decided that she had sufficient evidence to diagnose herself.
I first raised concerns about his lack of progression with speech when he was 2.5, but he wasn't far enough behind to refer then. He struggled to adapt to the birth of his brother. He was a bastard to get dressed (that would be his sensory issues, that he just couldn't express until he was older. He had an unusually long attention span. We veered from one tantrum to another and another. There were certainly signs when he was a toddler, but there was a lot of scope to mature out of them if if it wasn't ASD. An experienced HV may well recognise when they are seeing ASD, but they do not have the remit to formally diagnose and need to refer on through the appropriate pathways which can easily take over a year.
Autism is very personal. I know of at least 4 children with it in DS's school and there could potentially be more high functioning, undiagnosed children like DS was (and because he is so good at socially studying people and masking, school would never have identified it at this stage). There are some children who have transferred to our small, cosy school and need a 1:1 and modified curriculum to support them. Each child, like the NT children has individual needs.
DS needs down time, and warnings about transitions. He is very sensory about clothes, style, cut and fabric. He always struggled with the supermarket (which was awkward as his multiple food allergies meant I had to shop in 4 different ones when he was a toddler) He coped with the relaxed pace of nursery, but struggled with the increased structure of school and busyness of wrap around care; if I had to RTW, a child minder would be a better setting. He's been fortunate with the lovely children in his class and has good friends, but can struggle with unstructured socialising in a bigger group. He was well into school before he genuinely played with other children rather than alongside. He has got "easier" and happier as he's been able to express himself more. Parenting him is a blend of helping him be himself and helping him function in the world. Each child is different and has their own challenges and strengths. I love the person that DS is, but hate the frustration and anxiety that stem from the autism, that he could stay who he is, but just find life less of an exhausting effort.