Originally Posted by MBM3
Unless you purchase a Y fare the agent will tell you that you need to wait until the EUA sweep. In this situation, I would grab a full Y fare (which can be different than other "full fares" such as H) after seeing what flights have availability up front.
Buying a Y doesn't guarantee you the U/G, even if there are seats up front. If the flight has the golden U icon online then you'll get the upgrade. Otherwise it is a toss-up. I have bought many Ys (admittedly a high-rev market) and not gotten the U/G, as I am only a lowly gold elite.