My Xena was spayed this past Tuesday and she is good now. She weighs just over 4lbs. I took her in at 7:00am and picked her up at 2:30 pm. They had given her a sedation shot so she was very sleepy and really out of it until the next morning. I chose pain meds for her but only gave them to her yesterday and she doesn't seem to need them today. I posted on another thread that they shaved her way more than I thought they would, which I was disappointed about. Had I known I probably would have talked to them about shaving as little as possible. It's very noticeable. She has the dissolvable internal stitches and surgical glue for the external part and I have caught her licking it a few times. Today I put a t-shirt on her to keep her away from it. She also came home a mess and I can't bathe her for 10 days - yuck!
I know this is a lot of information, but I thought I'd share 'cause I wish I had known more before hand.
Good luck tomorrow - I know your puppy will be fine.