DD2 was 7 when she got her tonsils & adenoids
out last summer.
She'd had repeated tonsilitis and reduced hearing in one ear due to a build up of yuck!
The operation was very scary for us adults, but she was excited and not at all worried.
The fasting was awful pre-op. She would usually have a huge breakfast (porrige, toast and boiled eggs). Her op was delayed and by 2pm she was threatening to run away unless they fed her!
Post op she had a bit of bleeding from her tonsil beds, so was kept nil by mouth and given IV fluids over night.(in case she had to go back to theatre)
The advice is for them to start eating and drinking asap post op, so the delay in DDs case made her throat VERY painful the next day, when they said she had to eat before she could be discharged.
I wasn't prepared for just how painful it would be for her and found it very distressing tio see her in so much pain.
The up side is, the pain was short lived (4 days at most and getting easier all the time) and she's never had a poorly day since, after previously being constantly off school with ear infections, tonsilitis etc.
The gromit and removal of adenoids never caused her any pain or concern at all. Your LO will be absolutely fine, and the benefits are well woth it.