Originally Posted by
caphis
JetBlue lets you standby on one flight earlier or one flight later than the flight you're confirmed on, free of charge, as long as they're on the same day.
AskBlue says revenue standby is one flight before scheduled departure only, unless you're scheduled on the first flight in the morning, at which point revenue standby will be for flight afterwards.
Same day change is prior to departure, $40 fee, you can also choose colocated cities like JFK/EWR/LGA or FLL/PBI.