Welcome to Pet Talk, Tom. :-) As you can see by Jen's signature, she has introduced many cats, so I would follow her advice for the best results.

1 week is definitely a very short time for them to get used to each other. There has to be an entire re-arrangement of the kitty hierarchy, and that usually takes awhile, so the best advice I can give is to just have patience. I'm sure things will work themselves out....it might just take some time.