5-4 hours!! I'm still in bed then!
First of all, before I book I check the conditions. If it says checkin closes more than 1 hour (for European flights) before departure I don't bother, anything longer is either incompetent management or a ploy to get you to spend more time in shops whose rent is linked to income.
Then I check if I can get to the airport by train (and local shuttle bus where applicable) about an hour before closure. If there would be a long wait, again I don't bother - Europe's a big place, I can always find somewhere else to go!
So normally I get there between 50 and 120
minutes before scheduled departure. And I've never missed a flight!