As a lowly E, I've discovered over the past few years that the best way to get an upgrade is to work the phones until you get an agent that will do it! I've had one agent reject the upgrade request because I called too early, then hung up, called back, and scored the UG with another agent. Hit or miss..but if you want the big seat, be ready to invest the few minutes it takes to make a few calls!
Good luck.