We had this done when my son was 3, he also has asd and is non verbal.
Couple of points that may help;
we didn’t go for gas as that can make kids vomit, sedation through Iv.
ask for the first operation of the day, explain your son’s disability and it means he is going straight in at 9am hopefully and less time without food and upset
have fave choc biscuits for when he wakes up, he has to eat and wee before he’s discharged.
ask for ears to be checked also-
glue ear, etc. whilst he’s sedated you may as well have the ears and teeth, dentist in to check for any abnormalities whilst he’s under sedation, teeth x rays, wobbly baby teeth or decay, all can be sorted under sedation
we had allergy tests pricks dome also on arm to see for any allergies.
Watch out for the 7 day mark after op. This is when scabs fall off the tonsils and you can get a bleed, we did, watch for this around that timeframe. We had vomiting blood which freaked us out as we hadn’t been told and it was a blue light emergency as they may have needed to re cauterise the tonsils.
The bleeding stopped luckily so wasn’t necessary.
recovery was v quick apart form last point.