I got my WM card in 8/2010 and was finally offered the upgrade in May of this year. I started with a $100 cl and did the every 4 month increase until I reached $2000. When they upgraded me my limit increased to $2500. I maxed it out one time but balance transferred it, other than that I put about 100-200 a month and PIF. Keep in mind that if you do get offered the Discover version you lose your history on the WM store card and the WM Discover is opened as a new account. If you dont mind the new account then take it when its offered since you can use it anywhere and WM has good financing deals. Good luck to you 
and I'm sure you'll hear something soon.
Starting Score: 579