Since this is so close to her vet visit and vaccine I would call and let them know how she is.

Usually, my cats sneeze when they have a URI. I take them in to the vet and get the antibiotic for them. It is a one week course of treatment. Vita gets the URI often, and needs 10 days to cear it up.

I don't know how old she is. The other thing which causes sneezing is tooth decay.

Talk with your vet.