With spaying I think its best to do it before there first heat because it greatly decreases there chance of mammary cancer so normally around 6 or 7 months. It is very important to get the blood work before hand because they could have an issue with there liver or something else that you don't know about and if they were to go through surgery it could be very bad for them or kill them so you need to make sure everything checks out ok. Callie was spayed around 8 1/2 to 9 months I got lucky she didn't go into heat but she had a lot of issue as a puppy (thanks nasty puppy mills). She came home very sleepy and just slept the rest of the day and night did not want food or anything. She never licked at her incision so she did not have to wear a cone or anything. She did some how get a small infection and needed antibiotics but she stayed pretty calm the whole time. It was hard to keep her from jumping into her favorite chair so if I had known better I probably would have kept her in a play pen. Most dogs do lick though so I would get kiss e collar from here
The Kiss-E Collar they are amazing. Also make sure the vet pulls any baby teeth that have not come out.