So you need to leave or apply to extend your stay by December 26, 2012.
http://www.cic.gc.ca/english/visit/extend-stay.asp#extend
You may apply online or you may submit a paper application.
You don't say if you applied inland or outland. If you applied outland, I'd suggest waiting until you get the sponsor approval (which should be early December given current processing times) so you may include a copy of the sponsor approval letter with your application to extend your stay.
If you applied inland, you will need to submit a copy of the receipt for the fees and a copy of the courier receipt for delivery of your application to CPC-V (assuming you have one) as you will not have AIP in that time frame.
No matter what, you must apply to extend by December 26, 2012. As long as they have received your application to extend, you may stay in Canada under "implied status" (they act as if your application to extend your status has been approved).