In general, the earlier you buy the ticket the cheaper it will be, but you may find even greater deals if you buy at the last minute. Last minute is of course very risky. It may also not be so much about when you buy the ticket but more as to the travel date of the ticket that will determine how much you spend on it. Going to Hawaii in May is just prior to the busy tourist season so the odds of you finding a good deal is higher. You can find a bunch of tips and links about this at the source provided below. Good luck!
There really is no best time for Hawaii. Since it is quite popular vacation destination year round, you won t see prices dropping
Buy your tickets in January through Feb. March is Spring Break and April is Golden Week and that is when all the tourists come from Asia and Japan mostly during those times.
ASAP! The other guy is right Hawaii seems to stay pretty steady priced, but I would look on, cheap tickets, price line, orbits... etc and buy asap for the cheapest.
cheap and hawaii they just dont mix :)