Hi, my friend's daughter just had this yesterday morning. She's three too. The operation was scheduled for 7.30am and she was out an hour and a half later (I think, I received a text from her at about that time saying all went well). She had both tonsils and adenoids out as well as grommets.
My friend used to be a paediatric nurse and she was very impressed by how much things have moved on. Her daughter came out of the operation and was absolutely fine. I think they do the dissolvable stitches as well so she won't need any stitches removed. They released her from the hospital about 3.30pm though they did say she might have to stay overnight if the bleeding is bad or if she cannot eat. However, I went to see her (at about 5.30pm) and she was really tired and overwrought. Didn't help that her younger sister was winding her up. She made her cry and for the first time ever, she held her breath and went blue and then wet herself (she is properly toilet trained and been dry during the day for quite a few months).
Not sure if this is associated with the operation or just coincidence she discovered she could do this? Some tips...
Get her a present for post-op and keep telling her what a brave girl she is.
Make sure you have food (very soft food!) for her in the next few days that you have made that can be heated up at a moment's notice. I made very soft spag bol (I blended the bolognese and overcooked the spaghetti) to bring to them and she loved it. Lots of yoghurts and cool stuff... Lots of Calpol/Calprofen...
Do you have any other DCs? If you do and they are in school or nursery, keep them in there. Having another DC at home won't help!
Be prepared for any sudden changes in her behaviour. She may seem okay but it is a fairly big operation so be prepared for that.
I will pass on any other tips when I speak to my friend later. Good luck!