Looks pretty good.
Flying from Roto to ZQN will save some time, which is helpful, just beware of high one-way car rental fees.
You might consider driving to Wanaka from ZQN on arrival, and overnighting there. Stop at the famous Cardrona Hotel (pub) in-between for lunch/dinner. Wanaka is a beautiful town and worth a stop, probably cheaper than Queenstown, and will shave an hour off your drive time to Frans Josef (that can be quite a long drive as there are so many places you'll want to stop and take it all in!). You'll be back in Queenstown later anyway, so there isn't too much point of going there just for one night.
It's good that you are staying a few nights in Franz Josef, as the glacier tours are highly weather dependent. Even with three nights there, consider that you may not be able to get to the glacier, even in sunny weather (due to wind).
You'll be going through Te Anau to get to Milford sound, so it does seem like an inefficient thing to do both on separate days whilst staying in Queenstown every night. Maybe you can combine the two somehow?