I bought an international first class fare from Europe to MCO but the last leg of the outbound booked into economy (I have a seat in economy extra). Since MIA-MCO is a short leg, I can certainly survive. My question is: am I entitled/able to waitlist at the airport for a upgrade? If so, do I do it in London when I check in or in Miami during transit? Or can I even call i now if I see space available. This was bought as a BA fare and the flight is listed as a BA codeshare, so I assume I would call BA before the flight but deal with AA on the day of.

I remember threads where people who were denied boarding on one flight or who missed a connection were allowed to put themselves on the upgrade list of the new flight but I don't know if this is similar to that or not.