In most cases, the airlines will load at least some award seats at the outset of booking. The number will vary depending on their exepcted load factor. They may add seats later depending how seats are selling.

The general rule is to either book early or book late. Early, you catch the seats before anyone else can get them. Late, the airline might decide they have too many empty seats and decide to release some more award seats.

And the other thing is to travel when others aren't. Seats will be more available for off-season trips. I just checked Delta, and was able to find Sky Saver seats to Honolulu for late January, and HNL is one of the harder destinations.