Originally Posted by
JALPak
Then why would it depend on JL's flexibility? Fare rules allow the change then you would be fine. But whether they will charge you re-ticketing fee is a different story though.
Just the possibility that they might not like people turning up 60-90 mins before a flight and asking to be moved to that flight instead of a later confirmed one.
I've had JAL change tickets like this before, but not for same day flights.