Possible Upgrade Workaround??

I have a 3GS that is bought on release day last year and my upgrade date is 2/11/11, I am on a secondary line. My wife got her 3GS in March 2010 and her upgrade is 3/27/11. I just called ATT and they switched my number to the primary number and told me it would take effect on June 11th when my billing cycle reset. So in theory, on June 11th, shouldn't my upgrade date switch to June 2010?

 

As stated in the iPhone upgrade guide http://guides.macrumors.com/iPhone_Upgrade_Guide, the primary line gets an upgrade every 12 months, secondary lines are 18 months or longer for upgrades. This is confirmed because I bought my wifes 3GS in march of 2010 and her upgrade is 12 months later in March of 2011. I bought my 3GS on day one in June of 2009 and my upgrade isn't till February of 2011, 18 months later. So in theory, switching my number to primary line, ie. the line that pays the bulk of the bill, my upgrade date should be switched to June 2010 and my wifes to November 2011.