Just to make it more clear, only Mount Dennis the station will be opening on November 16, nothing else. One week later on November 23, would be when all the additional weekend trains to Kitchener and Bramalea begin.
Now to ask why they didn't just make one change for the 23rd only is beyond me. But I guess Metrolinx decided to act like Mount Dennis needs a 7 day trial run before adding more service, as if people that could now head to the many popular destinations on or near Eglinton more faster and convenient wouldn't be an instant hit on Day 1.