I often attend meetings at airports (like Sunday, 4/30 in Boston) and have tried to check in BEFORE my meeting so that I could race to the plane at the last minute without worrying. I have been quoted the 3-hour rule many times, but a different rule MAY apply internationally. I do know that almost every time I get to JFK for an international flight, even 2 or more hours in advance, all exit seats are always gone, filled by people who checked in MANY hours before, in their originating cities.

Bruce