Hi @wataru
This is only my opinion
Firstly you need to be settled here before you can apply for a partner visa , at least you can show something on your sponsorship that you have a job and most importanly you have an accomodation for her (rented place is enough).
Hence your fiancee can be soon granted a canadian citizenship going here in australia wont be a problem for her anymore as she can enter australia using canadian passport without any visa as per commonwealth country agreement. ( its limited though just not sure how long can she stay inside australia )but i think she can exit to the closest country in austarlia and back again to australia.
Once your already settled here in Australia and your fiance is already a canadian citizen way ahead of your scheduled wedding. I guess its up to you to move your wedding earlier so that you can lodge a partner visa for your wife
You also have an option of once your settled here in Australia apply for fiancee visa you might be able to do it mid of 2015 instead of waiting after your wedding before lodging a spouse visa. the only problem with that is definetely your wedding scheduled on December will not make it on time as the application nowadays is taking too long.
Hope this helps you and give you an idea
Best of Luck