I have a question about a great deal on a A-V 2011!

I am presently using a Norton three user license that will expire in March of 2012.  If I purchased a new CD via newegg.com which qualifies for a Norton $35 rebate, but don't install the new product until March 2012, would the license be good for 12 months.  Or, if I run the CD, would 12 months be added to my active subscription?  I'm sure if it would be it would also upgrade to A-V 2012.  Thank you!