Spend day 1 in Christchurch. Jet lag is brutal when you fly to Australia or New Zealand, it will affect you for days. Don’t get off the plane and take a long drive. NZ is wet. I spent three days at the glaciers, rained all 3 days and 3 days at Mount Cook, socked in with cloud all three days. Keep your plans flexible enough to deal with bad weather. I found the roads to be very easy, even driving on the wrong side. I would spend more time in Queenstown, less in Wanaka, Franz Joseph and Arthur’s Pass. Add in a trip to Akaroa.