Later. The bigger European airports are an absolute shitshow, with crazy long security lines and total chaos. We got to GDG 4 hours before our flight, and still had to sprint to make our plane, even with some kind agent pulling the soonest-departing passengers out of line. Same at Schipol-- it was a little more organized, but just as mobbed.
With 4+ hour lead times, pick the latest flight you can get. Otherwise you're up and on your way to the airport before dawn, and that's a lousy way to ennd a vacation. Get home, go straight to bed.