Twice this year I arranged my car to leave the hotel at 4:30am. At 5am, no line at business class check-in and I easily cleared custom by 5:15am. You do go thru another set of x-ray before boarding and holding area is too crowded for my taste. Y is 95%+ full and C is maybe 20% full both times so I hang around and clear final security last. Don't worry, if they got your bags in the belly, they won't take off without you.