Historically awards between the US and New Zealand have been one of the toughest things to book. Years ago Air New Zealand used to open up business class awards 60 days prior to flight. Then they stopped. With a couple of brief exceptions there really hasn’t been meaningful Air New Zealand business class award space in years.
Right now though there is peak business class award space, a little in November and January but quite a lot in December, on Air New Zealand between Los Angeles, San Francisco, and Houston and Auckland.