If the economy were in good health, the answer would have been "you should have booked two months ago". Fares to Oz/NZ are at their highest peak in the couple of weeks leading up to Christmas - I think the peak season usually starts around 8 or 9 December.
The first cheaper day for flying is usually 24 December, on the basis that you can get to Sydney but far too late (and far too knackered) to enjoy any of your Christmas Day - so it's the first day on which demand is lower. And if you are a real Christmas-phobe, you could fly to NZ westbound that day. You would leave LAX in the evening of 24 December, cross the dateline and arrive in NZ (or Oz) in the morning on 26 December without ever having had the 25th.
In contrast, the period from about 20 April to 30 June is the absolute cheapest time to fly to Oz and NZ. Those are the deals you are seeing now.
There have been years when sales have been poor, and promotional fares have come in nearer Christmas. But it is a very big gamble, esp as capacity has been cut back so much in the last couple of years for various reasons and there is still a real risk that one of the players to Oz (UA) could go out of business before then.