I'm sorry to paste my reply twice, sth wrong with my chinese input ,there are some words missing...
I don't think u can make an appointment in ottawa, Montreal, or Toronto before Xmas, cz I hv tried on Nov 5,2005, and all were fully booked this year. Only some vacancies are avalibale in Quebec City.So... I got my visa in Quebec city last week. Anyway, u can try , check the website I mentioned above, maybe someone will cancel the appointment. Good Luck!