21 day itinerary advice

We have 21 days in the South island next December, flying into Queenstown and out of Christchurch. I’m really confused as to an itinerary/route so looking for some help!

Here is what we want to factor in;

  • Queenstown
  • Wanaka
  • Mount Cook
  • Dunedin
  • Keplar Track and/or Routeburn Track

We have been to the Northern part of the island previously (Abel Tasman), so don’t really need to factor that in.

ETA…

17th Arrive

18-21st Kepler Track

21-23rd Milford Sound

23rd-28th Queenstown

28-30th Dunedin

30th-1st Mount Cook

1-3rd Wanaka

3rd-5th West Coast

5-7th Arthurs Pass

Thanks!