I was only asking because when my buns have gone in to be neutered and Pippa has just been spayed, I had a pre-op health check with my vet on the day, and once he was certain that she was absolutely fine she was spayed that day. Was just a bit concerned that they weren't planning to do that with yours because you said about giving her to a nurse. I didn't take pellets in as they told me they had everything there, but that does don't tend to eat as quickly so soon after a spay as boys do, and so she had a gut stimulant, to keep her well. She didn't want pellets, but I had left some herby leaves and parsley which is her absolute favourite with her and her bonded partner who went in with her, and she did nibble on those quite well. I would take something in, more like that for your bun to tempt her. I was a bit worried as well that she sounded like she was coming home a bit soon. Pippa went in early morning as well, but my vet never lets them home until after 1800hrs, so as to give them time to pee, poo, and drink if not eating, and by that time she was eating some parsley anyway, plus he likes to make sure they are very comfortable as well.
It is entirely up to you but I took a t-shirt in for Pippa to have on afterwards, because apparently does are more likely to worry with their sutures and make themselves sore, so Pippa's t-shirt stopped her doing that. She had a brilliant recovery, no problems what so ever, eating well the next day, post-op check up day 5. All was good.
