It is very tough because you feel you are not doing anything but that is not the case because not everything is in your control or on your timeline. Just work with your child on your own the best you can when you can because there is always a editing game going on . If it isn't a dr appointment it is an evaluation or some kind of test. Just trust that you are doing your best and the fact that it bothers you means you really care and are doing the right thing. Good luck and if you need some advise just ask

The reason he said to wait for school is because in your state they are most likely responsible for providing services. That would be not only at school but home as well if it is needed . Your child is going to need to be evaluated by their team before they will provide anything. Now if your child is in need of any meds or has behavior issues you may want to spend the time getting your child evaluated by a neurologist and a psychiatrist. And you may want that done anyway so you can use that against the school because they are only going to give you what they feel your child needs. We have a diagnosis from all three doctors and I can tell you the school has no one who can contradict that

On the side note, dont forget to look into how you can prepare him for school since he never attended any preschool before. Try to take pictures of the school entrance, classroom, principal, teacher to make some personal social story. Have a picture schedule in the class so he is prep for his routine.
I am in Canada so not sure how different it is from the States. I got a binder of what helps are there around my area. Sadly school does not do too much. Their resources is very limited and mostly on consultation basis. My son thrive more from the private therapy that we do - RDI, speech and OT. Good luck

You should look into your school district special needs programs. There should be a Special needs preschool he can attend until he goes off to Kindergarten next sept. if you have health insurance you need to look into ABA. Do not wait until next September!

Finally, remember that the squeaky wheel gets the grease. Don't be afraid to push for the services your child needs. The district will likely try to offer the least that they think they can get away with in order to save money- your job is to advocate for your child to get him what he needs.