After all, the name change to "Christopher Pike" happened very shortly before shooting began. For most of the development process, the captain was named Robert April (which eventually got used as the name of a separate character in the animated series)...
My understanding is that the April character in TAS was intended to be the original captain of the Enterprise, even before Pike. So the 1701 was launched, captained by April, then Pike, then Kirk.
ETA: Just checked the episode "The Counter-Clock Incident" and Kirk's opening log states that April was the first captain of the 1701.
But that was a retcon introduced by the writer of "The Counter-Clock Incident." Originally, "Robert April" was just an abandoned name for the character who ended up being named Christopher Pike. If you look at the first-draft outline for "The Cage" in The Making of Star Trek
, it was a captain named Robert April who went through all the experiences that Pike went through in the final episode. But when NBC publicist and screenwriter Fred Bronson wrote "The Counter-Clock Incident" (under the pseudonym John Culver), he invented
the idea that there had actually been a separate person named Robert April who had been the first captain of the Enterprise
. That idea has been widely accepted ever since, but it did not exist before 1974.
I mean, it's not the only time that one of Roddenberry's rejected captain names ended up being used for a different character later on. As I mentioned back in post #32, one of his suggestions, "Captain Christopher," was used for a character in "Tomorrow is Yesterday," and another suggestion, Boone (in honor of Richard Boone, star of Have Gun -- Will Travel
, for which Roddenberry was one of the most prolific writers), was used for the lead character in Earth: Final Conflict
. (In fact, that character was named William Boone, probably in honor of Shatner as well.)