New Puppy, Aggressive Cat

I just brought home the sweetest little 4 month old bored collie-poodle mix and my cat is FURIOUS. I understand why, this is her home and hes new but i dont know exactly what to do. I have been keeping them seperate with a touch of interaction but she juts likes to swat at him and its terrifying the little guy. He definitely knows whos boss and has no problem letting her run the show. Im hoping they will calm down in a week or so, is this realistic? Shes already less stressed around him after 2 days but i dont want him to get hurt. Thanks!