I won't be worried too much about the vaccine, she can have that done any time. I wouldn't mix that with the surgery tho. Usually the spay is done in the morning and the pup can go home in the afternoon/evening. Billi went in at 8 & I was allowed to get her at 3 because she was doing well. Some vets say a little later to be sure. Overnight doesn't seem totally necessary, but some Dr's do. It's preference I think. I just know I wouldn't have slept well if Billi stayed overnight. I'd have worried non-stop.
I'd ask your vet to elaborate about the reasoning for doing the vaccine the same day & what she means by her teeth looking good. That could mean a few things. Ask her pointedly if it looks like your little one is retaining any baby teeth & then tell her how you feel about the shot.
__________________  [I] Dani: Happily owned by Billi-Jane & Witten 
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