The original Star Trek pilot, The Cage, was filmed in December 1964-January 1965.You're welcome! Also remember that Star Trek is likely coming up in a couple of years. I don't think Gene Roddenberry would be butterflied out of his dream/concept of a "Wagon Train to the Stars", as he originally called it; indeed, his idealistic vision would likely be amplified. It's going to be interesting to see how exactly TTL's TOS differs from OTL's; maybe, for example, the original idea of a female first officer for the Enterprise stays in place.* In fact, from the very valuable book by Bob Justman and Herb Solow, "Inside Star Trek", most of the key casting seems to have been driven more or less by serendipity. It's possible, for instance, that Lloyd Alden, the person originally cast as the communications officer (he later went on to star in "Room 222" OTL) might stay in place, though I'd hate to lose Nichelle Nichols.
*Contrary to popular myth, NBC actually liked the idea of a female "Number One". What they objected to was having Roddenberry's girlfriend Majel Barrett cast in the part. In fact, they had more problems with the notion of Mr. Spock, especially his appearance - which they considered to be too "Satanic" - than with "Number One".