This is the right thing to do, and Lianne deserves credit for that call.
She says she wants to have the by-election as far away as the Council election as possible. She could achieve that by resigning immediately and having a by-election in August. Of course that means no salary and no parliamentary resources (such as phones) while campaigning, so I suspect she is not keen on that option.
The local elections have the votes counted 12 October 2013. So let’s assume Lianne resigns on 11 October 2013.
This means the Governor-General must issue the by-election write by Friday 2 November 2013. the writ must be returned within 50 days which is 22 December 2013.
You need to allow 11 days for special votes, 3 working days for a recount application and estimate 3 days for a recount, so really the election day must be at least 17 days before 22 December, so the latest possible date for the by-election would be Saturday 30 November.
If Dalziel resigns on 11 October, then the earliest day would be Saturday 9 November for the by-election. Every week earlier she resigns then that week could move earlier.
I’m hoping for any date except Saturday 30 November, as I’ll be tramping that weekend, so out of cellphone and Internet coeverage!