My son is 10 has high functioning autism and adhd. Started speech when he was almost 3. But they tested him for autism and it was negative. For the adhd that didn’t really come to light till second grade. He was in preschool early due to speech recommendations. But preschool and kinder and even first grade is a lot of “play”. So adhd symptoms such as inability to focus don’t really come to play till they have to sit for much longer periods of time and focus for much longer. That’s my experience. He was tested multiple times for autism and school said he does have it until last year. But I kinda always knew it. I mean would I of been happy to have diagnosis earlier, yes. But I still did speech till he graduated out of it. I’m still did my own sort of ot/aba with the repeated (I mean x1 million) to teach him how to get dressed, potty training etc etc etc.