The fifteen year reference in TWOK is already shaky without even looking at the chronology. If Space Seed is in 2266-67, then fifteen years later would put TWOK in 2281-82. But, we know without a doubt that the absolute earliest that TWOK can take place is in 2283, given the Romulan Ale. So, there's room for Kirk and Khan to be fudging the exact length of time when they speak of "fifteen years ago" and "a man out there I haven't seen in fifteen years."
I'd rather fudge the Romulan Ale date than the Khan date if it came to that, to be honest, even though on first glance it appears to be more accurate. After all, speaking in-universe, it could be a stardate rather than a year, or it could be a Romulan year.
Speaking out of universe, all we knew as of Wrath of Khan was that the movies took place in the 23rd Century, and even that fact was a relatively recent introduction to the canon. At the time, it was entirely possible for Space Seed to have taken place fifteen years before
and 2283 to have been some time before the movie. Maybe Wrath of Khan took place in 2298 and Space Seed in 2283. (A random example on my part that would be a little too on the nose thematically, but you get the idea.) It was only later that it was decided that the TOS dates should be 300 years or so after it originally aired.
Both dates having been called into question by the "new" (and since consistent) dating system, the fact that Khan and Kirk agree on the date, and the fact that the amount of time since Space Seed is more important to the plot makes it more important than the date on a bottle of Romulan ale, IMO.
BTW, how cool is it that Spock gives Kirk a book to read, and McCoy gives him the glasses to read it with? Those guys are great friends to have.
Right? It's enough to make you want to live life as they did... *Pulls out cast photo, holds back tears*

I think the big reasons the Okudas put TWOK in 2285 was because they had both the "2283" date on the Romulan Ale and a reference to Nimbus III being founded 20 years before TFF. Since the Romulans were in hiding before 2266 by their reckoning, Nimbus III had to be founded sometime after "Balance of Terror" (and probably after "Errand of Mercy" when it came to the Klingons). So I understand their reasoning, even if I don't agree with it.
Ooooh, that makes a bit more sense then. I hadn't realized there were more references to TOS in play. How specific is the reference to Nimbus III? Are they actually celebrating an anniversary, or or are they just speaking in general terms ?
Really? Even if we suppose Khan is someone going to keep this record down to the day, and even if we suppose Khan were able to keep an accurate count of days after a literally world-shattering event reduced the planet to near-lifelessness --- and think how hard it is to recall how long ago something a decade-plus was in your past, and that with the benefits of having seasons and calendars and newspapers and histories --- and if we suppose Khan were going to use this record to pin down how long he had been on Ceti Alpha V to the day, then we have to conclude he got rescued on the exact anniversary of the settlement. Which would ... be quite a coincidence.
No; I find it much easier to believe Khan was rounding, the way normal people do when they are making normal points. It was closer to fifteen years than to ten or twenty years.
That's not exactly what I meant, although Khan's enhanced intelligence
does make that more likely than it would for another character. I'd be more open to accepting the notion that Khan was wrong (for the reasons you stated, which are good reasons) if Kirk hadn't used the same figure independently when speaking about Khan. Now Kirk would have even less reason to be accurate than Khan, but I think the fact that they both agree should give the fifteen year figure more weight.
And I'm not pushing that it was
exactly fifteen years; just that it's probably closer to fifteen than nineteen, which is the current Okuda date. One would think that nineteen would be rounded up to twenty for normal people making normal points. I think somewhere between fourteen to sixteen years would be more in keeping with the film's dialogue, but if nothing else, it's a strong clue for timeliners sticking to the Okuda dates to place Space Seed on the later side of 2266 and Wrath of Khan on the earlier side of 2285. (Which, admittedly, jives with the notion that Kirk's birthday was in March.)
EDIT: I had also been under the assumption that the Okudas placed Space Seed in 2266, rather than 2267, which is what is actually in the Chronology. My bad. So we're talking about 18 years rather than 19, which could be brought closer to 17 depending on when in 2267 Space Seed takes place. I still think that it might be better to change the officially acknowledged date of 2285 to something earlier, but I do recognize that at this point we're only quibbling about an increasingly small number of years.
TC