You might want to talk this over with your SO. I'm leaning towards no. You are just now moving in with your SO. You need time to acclimate and not have a stranger move in starting in October for 3 months. That just sounds like a recipe for resentment and bother. If you do decide to let her move in, she should be the one to park on the street and cats aren't that bad to have around. Good luck and best wishes.