Due to multiple factors, expect to potentially pay more when booking in December. For low rates, June can be a great choice for travel to New Zealand. Flights to New Zealand from Redmond in June are about $1,259 on average during June, but can be found for as low as $779.
Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Redmond to New Zealand as you normally would.