We're flying back on AA from Buenos Aires on a Monday at the end of October with the hope of getting upgraded to business class. Do you think we'd have a better change if we flew on Tuesday instead?

We're flying to DFW. Since DFW is AA's megahub, we're not sure if it matters if we fly Monday or Tuesday, the result might be the same. Do you generally have less chances clearing to a megahub like DFW? Thanks for any feedback.