Hi Yas1362, my son is now 6.5 and he is doing generally pretty well. He is still having a lot of different therapies and continues to have a range of challenges and differences to neurotypical kids, but overall my level of concern about his future and his abilities is much less than it was when he was younger.
He has always struggled to be in group settings with other children, so when we tried to put him in preschool at age 3.5 he did not cope well. He cried and was very upset about being left there, and developed severe separation anxiety. I am in a number of online groups for parents of autistic kids and I discovered that it is very common for them to find school settings very challenging and overwhelming as they often don't cope well with the pressure of many expectations and people to deal with. We decided to pull him out and have been homeschooling. He's very happy with that arrangement and we are doing some extracurricular things, going out to playgrounds where he gets to meet other kids, etc. Like a lot of autistic kids, he finds it easier and more enjoyable to interact with adults than with his peers. So we're gradually working on getting him comfortable with activities where there are groups of kids. He is in a gymnastics class where he tends to run off at times when the kids are doing something he's not feeling into at the time, and doesn't consistently listen to the teachers' instructions, but they are very patient and tolerant so it's working out ok! The teachers tell me that they've seen kids like him before who have done just fine and ended up becoming coaches at the centre. So that's encouraging lol!
He is smart and has picked up a lot of things on his own. For example he can read at quite an advanced level even though nobody ever really sat down and tried to teach him. He isn't great at listening and taking instructions so he would probably be a lousy school student. But can learn things alright when we make it fun. So I teach him maths by using his snacks and putting them in rows to get him to add and subtract etc.
His social development and communication has been a bit delayed compared to other kids, so although he had a great vocabulary when he was 3, and could recite long passages from TV shows he liked, he couldn't really answer questions or have anything like a conversation. Once he was able to answer questions, he still didn't ever just look you in the eye and talk to you, we would only talk while playing with things and then we'd talk about the things we were playing with. It's only now that he's 6, that he's started to just come up to me and ask questions about how things work, and just have what I'd consider a 'chat'. He also used to walk away whenever he saw a group of children playing together, and still isn't very keen on that kind of thing, but over the last year or two he's become quite comfortable to walk up to random children at a playground to ask them if they'd like to play.
For people asking what programs might be useful - it depends quite a bit on what the individual child's delays/concerns are. For me, one thing I have found really helpful was ESDM, and there is a book, a manual for parents, called 'An Early Start For Your Child With Autism'. I didn't agree with some of the techniques, such as the 'extinction' method where you totally ignore the child if they are having a tantrum. I always cuddle my kid and co-regulate, and comfort him! But most of the techniques are about things like making sure you get down on the floor where your child can easily see you, using a fun happy tone of voice and making big expressive gestures and facial expressions, singing and making everyday conversation into a song, etc. That's for kids who aren't engaging/making eye contact etc. The good thing I've found about DIY therapy is that you can take the parts you agree with and ignore the rest. The main thing I got from the ESDM manual and our in-clinic therapy, was learning great tricks on how to engage children and get them interested to play, which then gives you the opportunity to teach and connect with them in the process. It works well with all kids and not just those who are autistic.
There was an article about research by Andrew Whitehouse (Australian researcher) who created a program for toddlers who were showing signs of autism - apparently many of them who participated (the techniques were taught to the parents who then carried out the program with their children) ended up no longer matching the criteria for autism diagnosis. It was based on teaching the parents how to recognize their child's individual communication style and strengths, and then build on that. Andrew Whitehouse heads a clinic that offers therapies and programs, which probably aren't available to people outside Australia, but you could look up their website to see if there are useful resources.