SDR advice

My 4 year old is having an SDR on Thursday (in Australia).

I feel as though I have been preparing him as much as I can in an age appropriate way, but I’m terrified of the immediate after

If anyone has had this surgery or has had a child who has had this surgery I would really appreciate any advice, anything you found really helpful to take to the hospital? We will be about two hours away from home, so I don’t want to forget anything.