Firstly, get a meeting set up with his parents. They are the experts!
Does the whole class use a visual timetable? If so, that may be good enough, or it may help to have his own personal copy, maybe broken down into smaller segments. He may need every part if the day specified, toilet, wash hands, milk time on carpet, line up, playtime, etc. More detailed than the whole class timetable, perhaps. Have it on a velcro strip, take off the activity once it's complete.
If there are any times when behaviour is challenging, you need to find out the underlying cause. Sensory questionnaire to find out what might trigger meltdowns, inappropriate behaviour. Is he hypersensitive to sound, lights, smells etc.
ABC analysis is useful, antecedent (what happened immediately before incident, behaviour, what actually happened without adding an emotional response, consequence, what happened to him as a consequence. Helps you to understand how to avoid the situation, how to anticipate the triggers and how to avoid actually rewarding him for inappropriate behaviour. (if the consequence is time out, he may be seeking time out.)
If his communication isn't great, make sure you say his name and get his attention before giving him an instruction. Use very simple language. Allow time for processing. If he doesn't understand, don't rephrase too quickly. Give him time to process and respond. If you keep rephrasing, he'll have to start from scratch each time.
Keep instructions basic, one at a time, until you find out how many he can take in one go. Often only 1 or 2 part instructions at a time. Let him finish before going on to the next.
Find out what rocks his boat, what can you use to reward acceptable behaviour, stickers of dinosaurs? Thomas the tank engine?
Get some training if you can. Widget (communicate in print) is good for symbols for timetable etc. Social stories training would also be useful.
Ask more as you think of things. 