I'd start looking now. We're going next June as well, and I booked our flights back in August (we used airline miles on American this trip).
We actually own at the Marriott Ko Olina, and have been many times. I always start looking for airfare at the 330 day mark, and when I find a good rate (using miles, we always do that), I book it.
We fly out of the DC/Baltimore area, so have 3 airports to choose from (although BWI is preferred, this trip we're in and out of DCA but going for a month).
Not sure what airport is closest to you, but if you have alternates to look into, it may be worth it (like if you're close to Tampa or Orlando look at either?).
I prefer to only have one stop, but for the first time our next trip going over we have two stops. It was worth it to me to get first class with the lowest mileage (return through DFW is one stop and lie flat seats, which is so much nicer).