I second waking them up to take pain meds. And, obviously, make sure it is liquid medicine. When I was nine the pain killer was liquid and my mom would let a popsicle melt into the medicine cup and then I would drink it all down. It worked really well and for the first day this is all I had. I just was to tired to hold the popsicle myself but I wanted something.
Also, if you have a bleed out (I did on day 10 as an adult) you should know it. But just as a precaution, I would tell your child to tell you if there is a weird taste in their mouth, because it tastes like metal or iron. I've heard people say you can miss a bleed out because it just drips down your throat, but for me personally I cannot imagine missing it. It tastes weird, your mouth is full of spit & then bloody spit & then small clots & then for me I started vomiting. This is all in a matter of a minute or two. Maybe I'm unusual but a red popsicle wouldn't have confused me.
Don't stress out about having a bleed out, a VERY small percentage have one. But if you do have ANY bleeding go directly to the ER. It is simple for them to fix, but if you delay it can actually kill you. I really did not know this prior to having a bleed out. Again, I'd write down all your questions & ask the doctor. In my opinion, the more info I have about a surgery, the better.
On a totally positive note, I am a strep carrier and am sick constantly with tonsils in my body, ear infections, strep throat, etc. When I was 9 & had them out I hardly even had a cold for the next 15 years. Then they started to grow back & I spent a year and a half in bed with strep throat and ear infections. Very confusing for me. Had my tonsils out a second time and haven't had strep or an ear infection since. So it really does fix the problem & is worth it.