Group travel Sydney AU -> NYC mid December – ways to book flights?

A group of ~15 musicians need to travel Syd -> NYC in mid December for a week and is looking for the cheapest flights, ideally around $ 1000pp. What is the best strategy:

  • Contact airlines for group booking as early as possible.
  • Contact travel agents now for the same.
  • Keep eye on ticket prices/sales as individuals would do and book individually when prices drop.
  • Contact airline only when it has tickets on sale for group booking?

My concern is if I ask airlines to quote for the group booking now it will not will no give much discount compared to the sale price which I hope they will have later. Is there any value requesting group quote from airline/agent vs booking individually if you want the cheapest fare?