A work in progress....obviously.
No one is really sure just when, exactly, the human race started working on actual time travel. Rumor has it that the old U.S.S.R was one of the first organized (if you would classify the old U.S.S.R as 'organized') government bodies to say “Yes, (or “Da” as they said in the old U.S.S.R) let's actively look at traveling through time and, maybe, space.” Every piece of data I've ever seen on the subject also says that the Russians started this back as early as the 1930s...a sort of 'side job' while they looked to the stars and wondered how to shoot a monkey or a dog into the stratosphere. Ah, those crazy, vodka soaked, Russians. By the 1950s more and more countries were looking at time travel, secretly of course, as a means to not only make money, but to get a 'temporal leg up' on the impending Cold War.