I know you're feeling nervous. The only thing you need to do is to keep her from jumping. Kacee was spayed on October 21st and I was sooooo nervous, even though I trust her dr implicitly. She came home that evening and we slept on the floor!
She spent a very restless night, but was feeling much better very quickly and back to playing ball in no time. I just noticed for several weeks after the operation that every once in awhile you could tell she felt a twinge by the way she acted, but even that went away eventually. She had internal stitches. Good luck and let us know how she does Thursday evening.