I’m a teacher in a school Nursery class (England)
I feel that at this point in the academic year, the staff should have built a relationship with your DS and worked out his triggers and developed some strategies for dealing with him.
The main issues in a Nursery classroom that I have observed over the years are transitions and the general business/over stimulation, and also dealing with the fact that they are one of many, so they have to tolerate delay in having their needs met, or communication issues- frustration at not being able to communicate their needs/wants (These all apply to NT as well as SN children)
They are logging incidents, so they should be able to see a pattern and identify his triggers, then go from there.
If it’s transitions then pre-warnings, timers, visual timetables, if it’s over stimulation then a quiet place for some timeout or even going on a little walk, if it’s sharing/turntaking/tolerating delay then sand-timers, social stories, can be effective. With communication difficulties they need to keep their language succinct, makaton, pecs/pictures/symbols, social stories.