Hello all, quick question on confirmed flight changes / "same day" changes. Say I have a flight departing Sunday at 5pm. If I want to change to a flight the day before, Saturday, at 10pm (less than 24-hrs earlier), would that be covered as a "free" change"? The premier benefits says 24-hrs but the footnote says "same day" and I am not sure which is correct in practice.

Is it best to do this at the airport?