If it is Aspergers or an autsim spectrum disorder I don't think waiting another year will necessarily help him and he will stand out as being so much older then the other children. Usually boys born in the last few months before the yearly cut off (31 July) get held back not one who is in the older end of the age range for that year's kinder as your son is.
I would be getting him assessed before school starts as then he may be entitled to an aid who will help him transition into school.
I know my POV comes as a teacher and not a mother but I hope it helps.