When its bifurcated final season begins Sunday at 10 p.m. EDT on AMC (with seven episodes, to be followed by seven more next year), the second of those final hours will be shooting, while the fifth of seven final scripts will be taking shape on the page.
The looming end has taken root in the "Mad Men" conversation among fans, even as they mark time waiting for the 14 new installments. Meanwhile, Weiner, as the auteur of this landmark drama series, voices both resolve and wonderment at his task of bringing "Mad Men" in for a landing.
His goal, he says, is not to wallop the audience with a grand parting shot, but something more gently profound: "to leave the characters in a place where they're going to be in viewers' imaginations forever."
Weiner has said many times he hit upon some semblance of that "fitting end" several years ago.
And yet: Pulling the plug on a TV series goes against every instinct of the person in charge, he says - the person whose primary duty is to keep the show alive and well, week after week.
Even for a series veteran like Weiner (who was a writer-producer of "The Sopranos" as well as the sitcom "Becker"), his mission to end "Mad Men" is "a totally antithetical thing, an exercise that is outside my realm of experience."
Viewers will remember that at the close of last season, which spanned the stormy year of 1968, Don Draper (series star Jon Hamm) was left in disarray. He had been sidelined by his ad agency after suffering a meltdown at a client meeting. His loving wife, Megan (Jessica Pare), walked out on him after one too many broken promises.
The 1960s have been hard on Don. A man who, years before, assumed another man's identity, he has shaped his sense of self, and his career, from cultural models that seem to grow increasingly outdated as the '60s wear on. Don - however charismatic and commanding his image - is on a downward spiral as he hits middle age, fast becoming an old fogy in a youth-obsessed era. Or so it may have seemed to some viewers.
Weiner doesn't see him that way.
"There's been a constant assertion about Don being out of touch, and that, by 1968, his style of advertising isn't working anymore. I've never felt that," Weiner says. "What I do feel, particularly last season, is that society has caught up to him. Identity issues caught up with society, which made the society more like Don. He's never been MORE in touch.
"The world is changing. That was the original intention of the show. And change makes everybody feel out of place."
Indeed, there have been signals that Don, swamped by painful recognition, is braced to take corrective action.
Last season's fade-out found the man who, at the series' start was fiercely guarded about his past, coming clean to his three kids: Don stood with them outside the former whorehouse where he, born Dick Whitman, was raised as an orphan.
Now, how does the new season pick up the action?
As usual, Weiner made sure the preview he shared with TV critics was accompanied by a laundry list of details not to be divulged: things like when it takes place and what's going on with Don's work and private life.
What, then, can be shared? That the episode, written by Weiner, is richly satisfying. That the cast (also including Elisabeth Moss, John Slattery, Vincent Kartheiser, Christina Hendricks and Aaron Staton) remains terrific. That the series seems headed confidently down its home stretch.
Pretty much the rest is meant to stay hush-hush.
But secrecy is not simply an obsession for Weiner. It's a marketing strategy that serves "Mad Men" well.
"This was a decision I made at the show's pilot stage," he says. He pointed to January Jones, who plays Don's ex and at the show's inception was still his wife. "She was not part of any of the press material for the first season, because I didn't want anyone who watched the pilot to know until its final moments that Don was married."
Weiner laughs, recalling the first table read for this obscure new series on an also-ran network as he demanded confidentiality from his cast.
"Everybody looked at me like we'd be LUCKY" if spoilers were a problem for this show. "They were thinking, 'You REALLY want us to keep things a secret?'
"Not all entertainment has to be this way," Weiner acknowledges, "but I thought that the surprise of our storytelling would be a smart marketing decision. Luckily, AMC agreed, right from the beginning." And as Weiner hoped, it helped get the show noticed - and still does.
Now the end is in sight. How to pull it off in a way that does justice to the series and its fans? And to viewers who have yet to discover it, and won't until all the cats are out of the bag?
"If 'Mad Men' continues to be watched after its ending airs, whoever approaches it will know how it ends," Weiner muses almost wistfully. "However we end the show, there won't be any more secrets. That's kind of weird." He means to leave a show behind that will satisfy latecomers, too.
But that's all ahead.
"Before then," he declares, "we've got a lot of ground to cover."