If your upgrade hasn't confirmed by the time you leave for the airport, I usually ask to be put on the list when I check in. And then as soon as I arrive at the gate for the connecting upgraded flight, I **pleasantly** ask the gate agent if I am on the list...you'd be surprised at how often this gets messed up (i.e. DCA-DFW-HNL, with an upgrade DFW-HNL that doesn't get entered at check-in)