My vet also keeps rabbits overnight after getting spayed or neutered. This does sort of stress me out, but I do have confidence in them and have not had any issues with leaving them. It is mostly stressful on me as I am very protective of my rabbits and don't like them to be away from me, I have a hard enough time leaving them with my mom over night.
I would give the vet a call. You may not have heard anything yet as they could be really busy or just not ready with an update yet. Things do happen which can delay the surgery and the does delay when they are ready and recovering. Just give them a call and ask how she is doing.
When you call, ask when you can pick her up. They usually won't do it first thing in the morning as they would want to have time to check on everyone and make sure they are doing well. I do understand wanting to pick up sooner that later, but you also want to make sure that she is ready to go.
When you pick her up, make sure you get some pain medication. This is usually metacam, but can be something else depending on what the vet is comfortable giving. Whatever it is, make sure you get something.
Also make sure the cage is ready for her. Clean bedding but no shavings or other litters; blankets, towels or newspaper are best.
It is also important to not put her in with her partner right away. She still needs a chance to heal and you need to be able to monitor that she is eating and drinking. You can have the cages close to each other and let them interact that way. After about a week, they can have supervised time together but I would hold off on putting them in the same cage until at least 10 days after. You will need to be careful that they are still getting along as she will smell different and the time apart may lead to some issues.
Her partner looks super bored and lonely. Wish us luck!
