According to JetBlue's website you may check in at least 6-hours before the flight all the way up to 20-minutes before the flight. *I would use caution though as many airports encourage passengers to arrive up to 2-hours or more to get through necessary security screenings.
As earley as you want
That info is on JetBlue website
as early as 4 to 5 hours prior
You can get your boarding pass in advance while you're still home and you should be at the airport an hour to an hour and a half depending on which city before your flight takes off
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