Originally Posted by UGBSM

As a DH pilot, after adding your name to your PNR, you should be able to select/change to any regular coach seat (not comfort+) that shows available at any time on delta.com. 24 hours prior to departure additional inventory seats are released and you may see that more coach seats are now available to select. In addition, available comfort+ seats are also released 24 hours prior and you may now select one of those for free.

As departure time approaches keep checking for comfort+ availability, particularly if there are first class seats showing available because medallion customers that get upgraded to first class tend to be holding comfort+ seats that now become available to you! Don't wait too long because an hour prior to departure you cannot select/change seats online. Within an hour of departure you *might* be able to ask an agent to switch you to a comfort+ if you see that there is one available, before they start assigning the non revs.

Of course you may never select a FC seat but you may use delta.com to get on the upgrade list for FC ... behind a gazillion medallions of course. But at least you will be PSUP so you are ahead of all the S2s and S3s.