It's through this promotion that I found this website... So I will share the conversation that I had with MP earlier this week. I am booking ORD-LAS for March, and wanted to use that reservation to allow for the Premier extension through Jan 2011. However, I was afraid of the cost of the flight would rise if I had to wait until my account reflected Premier status. They told me that although my account wouldn't show up as Premier until the 14th (as mentioned by gevflyer), any round-trip reservation made before then, and after you register for the promotion, would be enough to trigger the extension.

I will check back on the 14th to see if the changes have been made.