Spock makes his entrance.

[T'Girl]

In the episode The City on the Edge of Forever, Kirk, Spock and McCoy travel through time to a American city during to the 1930's. McCoy jumps into the Guardian first, a few minutes late Kirk and Spock go through. But who arrives in the past first?

On the surface it might seem that, of course, Kirk and Spock arrive first, it obviously a earlier date and they have to wait for McCoy's arrival. I believe that from a time travel point of view McCoy "arrived" first. Let's say that Kirk and Spock arrive on October 1, 1931 and McCoy arrives November 1, 1931, in the city of Chicago. It seems to be getting colder over the course of the episode and would nicely make the romantic movie Possessed, Edith Keeler's "Clark Gable movie." Even though they enter the Guardian within minutes of each other, McCoy has less distance in time to transverse, one month less. While McCoy is screaming in that dark alley in early November, Kirk and Spock shoot past him in time heading for early October, which is farther back in time. McCoy arrives first.

There's also the matter that all three enter the Guardian while basically in a alternate (Nazi's win) universe, how do they get back into the prime (Nazi's lose) universe to set things right? Simple, all three travel back farther than the historical branch point, by traveling back beyond the point that Keeler isn't killed, they rejoin the prime universe.

If, hypothetically, Kirk or Spock had done something to create a new alternative universe prior to McCoy's appearance , then when November 1st rolled around McCoy wouldn't have appeared in this new alternate universe, because he "already" appeared in the prime universe while traveling back from the Guardian. For Kirk and Spock (in their new universe) no one appears on November 1st. And for McCoy, no one is there to prevent the saving of Keeler life and the creation of the Nazi's wins universe.
---------------

In the last movie Spock and Nero travel backward through time, who arrives first? Spock in 2258, or Nero in 2233?

Really Spock, he stopped time traveling long before Nero, not after.

Both entered the blackhole in 2387, Spock traveled backwards through the prime universe 129 years and re-entered the universe in 2258. Nero continued on, he traveled backwards through the prime universe 154 years and re-entered the universe in 2233.

Given that Spock re-entered the universe while Nero was still traveling backwards, Spock should have re-entered the prime universe, a universe where historically the Kelvin encountered nothing unusual on Kirk's birthdate.

25 years after Nero re-entered the prime universe and created a alternate universe, he should not have been able to capture Spock, because Spock had "already" re-entered the prime universe, prior to it splinting into the alternate one. There would have been no way for Spock to have gotten across into Nero's alternate universe. Nero had no more chance of grabbing old Spock at that point, than he did young Spock serving on the original Enterprise with the original Pike in 2258. Nero wouldn't have access to either of them.

In order for Spock to "re-enter" the alternate universe in alternate 2258, he would have had to have been time traveling backwards through the alternate universe in the first place, from the alternate future not from the prime future.

If you see what I mean?

 

[Mr. Laser Beam]

In the last movie Spock and Nero travel backward through time, who arrives first? Spock in 2258, or Nero in 2233?

The question is irrelevant. Spock and Nero could have appeared, in their respective time periods, simultaneously. In fact, in a very real sense, that's the only thing that could occur.

 

[A beaker full of death]

This is some silly shit right here. This "meanwhile, in the past" stuff is nonsense. Kirk and Spock went to an earlier period in time than McCoy. It's mere sophistry to frame it as "McCoy arrived later before Kirk arrived earlier."

 

[Timo]

...Also, while the model of branching timelines is intuitively pretty neat for scifi purposes, there must be inifinite brances (of infinite fineness) occurring all the time. Kirk and Spock's arrival must have had a butterfly effect on the "prime" timeline, so McCoy would indeed arrive onto an "altered" timeline in every case.

However, it makes sense to assume that each branch we can observe is actually a fairly nebulous, "thick" entity where a zillion closely related timelines all represent roughly the same history unfolding. A zillion McCoys would have arrived in the past and encountered a zillion Kirks, Spocks and Keelers, with the top of the bell curve (the half a zillion most prominent timebranches) being visible to us as the adventure that successfully prevented Keeler's survival and enabled WWII.

The inevitable consequence of the branching model is that everything is possible. Beyond that, it's just statistics vs. drama. We may be watching the most likely turn of events, or we may be watching the dramatically most interesting turn of events - and in both cases, we can rest assured that a zillion Kirks saved Keeler, a zillion others were stopped not by their conscience but by an unfortunately placed banana peel, and a zillion more decided to slum it in the 1930s and use their mnemonic memory circuits for evil.

Timo Saloniemi

 

[Nardpuncher]

I don't want to sound rude as we're all on a board to discuss a TV show, but really long posts that try and reconcile time travel stories that weren't really that complicated surprise me.
Sorry but I only read the first three paragraphs.