If you SDS, you can't really be on the upgrade list until your standby clears. Typically, the GA will clear upgrades first, then standbys, so it's too late. (If it's a flight with so few medallions that upgrades don't fill F, you have a chance. It might also be possible for a GA to clear (some) standbys prior to clearing all upgrades. I won't say that chocolate has anything to do with that.)