The morning is the worst time at EZE

Looking at the arrivals page on aa2000.com.ar - not too many planes arrive at the same time as the AM flight . Only the Turkish from Istambul is a widebody.

Seems to be all 737s and A320S when it leaves , so departures shouldn't be too busy.

Still as said above , if you can do online check in , this would be much easier. However they might look at you strangely when they ask , you are travelling to Mexico and where are you coming from sir?