It'll probably 7 or 8 November.
So the FIFA window is 6 - 14 November Northern Hemisphere time which is 7 - 15 November in NZ time to complete both legs.
There will be about a week between games.
So could be Wednesday 8 November home leg at Westpac and Wednesday 15 November away.
Complicating factor is the Rugby League World Cup with games scheduled in NZ at the time:
Saturday 11 November NZ vs. Tonga 5 pm Hamilton
So you can probably rule out any game on Saturday 11 November.
Other than that, the Rugby League World Cup games fortunately don't conflict (the quarter-finals are 17, 18, 19 November)
The NZ team play Scotland Sat. 4 November in Christchurch in a group game.
I'm not sure anyone will be giving two sharks about some piss-weak rugby league games.
I feel Wed-Wed is less likely this time as it's the NZ leg first.