http://www.cic.gc.ca/English/immigrate/ ... spouse.aspThe problem is that it takes awhile so logically you should get married now, but if you do that then you are no longer a non-immigrant in the US and should apply for AOS.
So you either enter Canada, get married and apply for AOS here which takes even longer, or get married in the US and apply for AOS there even though you have no interest in it and apply to sponsor her from there which will be quicker.
Don't ask me why it's quicker to get it from outside of Canada, that's a question for bureaucracy. Have a look at:
www.roadtocanada.com
Steve.