We always plan to arrive at EZE no later than two hours before departure even though we stay a 2 hour drive away. Priority check-in helps as does departing around midday early afternoon. More often than not we arrive earlier which is all to the good.

Evening departures are a different kettle of fish as is getting to EZE during rush hour so I agree with the others. No point in leaving it late as you want to be relaxed.