Prime Minister Jacinda Ardern has previously been reluctant to pin opening the Auckland boundary to a certain day, given how it throws out any bottom lines for safety.
But several factors make this no longer politically tolerable: Auckland's three months and counting in lockdown, Ardern's and Labour's dipping popularity in the polls, and one poll showing more people thinking the country is heading in the wrong direction than the right one.
Ardern even conceded as much yesterday in saying: "We know people want dates. We're looking to provide that level of detail."
The decision to allow travel in and out of Auckland from December 15 will mean a lot more cases in a lot more places.
There will also be a lot more cases in Auckland before travel begins.
Previous modelling showed case numbers peaking at between 200 to 300 a day and Auckland hospitals coping, but household bubbles will be no more from early December, when Auckland moves to the Red setting of the traffic light system.
It's true that the new system provides more protections than level 2 because there are fewer opportunities for the vaccinated and unvaccinated to mix and mingle.
Aucklanders will be able to kick off the lockdown cobwebs and hang out in other people's homes for dinners and end-of-lockdown parties.
No one should begrudge them that. It will be some much-needed social interaction after the longest of New Zealand lockdowns.
But we also know that household gatherings are the main way Delta has spread, and while Red will mean these gatherings will only be allowed for up to 10 people if anyone is unvaccinated, this won't really be enforceable.
And given the two weeks in Red before travel outside the city is permitted, expect case numbers to start tracking up just in time to boost the chances of the virus spreading to other regions.
Aucklanders will understandably want to visit loved ones in all corners of the country, and to host non-Aucklanders, so don't be surprised if an enormous number of people want to come in and out of the city.
Covid-19 Response Minister Chris Hipkins talks about the potential danger of cumulative risk when explaining why the international borders aren't more open, and this is exactly that scenario.
The risk will be mitigated by the requirement for travellers to be fully vaccinated or have a negative test.
(Requiring both would be more effective, but Ardern must have thought she was already facing enough criticism for effectively having two classes of people.)
It will be further mitigated because we're coming into summer, with more people outside rather than inside, and because 90 per cent of eligible Kiwis are expected to be fully vaccinated by December 15.
This also translates to about 420,000 people aged 12 and over who are less than fully vaccinated, as well as 760,000 children too young to be vaccinated. While they're less likely to catch Delta or pass it on, they're not immune; about one in five of the cases in the current outbreak have been under 12.
And we know that the virus, as it did in Auckland, is most likely to spread into pockets of the vulnerable and the unvaccinated, where it will exacerbate existing inequity.
It will disproportionately affect Māori and Pasifika, the young, and the rural.
First-dose coverage (which better reflects where double-dose coverage might be in a month's time) among eligible Māori sits at 78 per cent, and for eligible Pasifika at 89 per cent. Both ethnicities are more susceptible to severe health consequences if they get infected.
For 12- to 34-year-olds, it is 87 per cent - slightly lower for Pasifika in that age bracket, and much lower for young Māori.
And in the regions, there are pockets of the West Coast of the South Island, Tairāwhiti, Taranaki and Northland between 70 and 80 per cent. In the Bay of Plenty, some parts are as low as 66 per cent.
How much damage there will be is hard to gauge.
With 90 per cent coverage of the eligible population, Te Pūnaha Matatini modelling estimates 461,893 cases and 1557 deaths a year, with 878 peak hospitalisations.
The traffic light system, though, includes public health measures stronger than those assumed in the model.
Part of that toolkit is localised lockdowns, which will be accompanied by surge vaccination teams. How this will be deployed, and how effective it will be, remains to be seen.
Lifting vaccination rates across those regions, Māori, Pasifika, and young adults will undoubtedly help, as would vaccinating those aged 5 to 11 - though the latter won't happen until next year, if approved.
Another factor is the effectiveness of case management - including those isolating at home, which will be a majority - reaching and isolating close contacts, and much more surveillance testing.
Health chief Ashley Bloomfield describes this as the new "sustained and sustainable" response, which is meant to keep cases so low that hospitals will be able to go about their usual non-Covid business, as well as care for cases nationwide.
It will, as always, be a collective effort.
People should get vaccinated, encourage others to do so, and continue to follow the rules whatever the system or setting.
And the Government has to ensure the vaccine is available in hard-to-reach places, where communities are encouraged in a culturally concordant way.
It needs to build capacity to manage and quickly contact-trace the volume of expected cases nationwide.
It needs to ensure suitable care for cases at home and in MIQ, conduct widespread testing using everything in the toolkit (including rapid antigen tests), and prepare the new system - including the local lockdown lever - for all scenarios.
It's a lot. It has a month to get ready.