ninenot wasn't making a distinction. He was categorically denying the last supper was mass. The Catholics I know, who are my age, learned the action of Mass consisted in Jesus offering Himself as (priest and victim) as a sacrificial offering of propitiation - which is what happend at the last supper and which Trent, ect ect, taught was when the Mass was instituted.
Finally, I read GBC's cite as saying that the Last Supper, in and of itself, was NOT a "Mass," insofar as the Sacrifice was NOT consummated at the Last Supper.
NONE of your citations stated that the Last Supper was the first Mass. None.
All of them did state that the LS was the institution of the Holy Eucharist--a point which I made, as well.
Repeat--it's tiresome--come up with a citation which states, categorically, that the Last Supper was the "first" Mass.
Put up or shut up.