I think its general anywhere though;3 hrs before.Here in Ottawa,we had a 6 am departure for Aruba via Newark,last January.Customs didn't open until 5,and there wasn't anyone at the airline counters until 4 or 4:30.On the other hand if you are there early,at least you'll be one of the first in line to go through security and do customs.Sometimes that line{customs}can be very long,and seem a lot longer when you have a plane to catch.