TOS is fairly consistent within itself and just about
holds together, placing the series in the early years of the 23rd Century. It's only with later incarnations that problems start to arise, beginning with TMP:
DECKER: NASA. National Aeronautics and Space Administration. Jim, this was launched more than three hundred years ago.
That would put TMP into the 2280s at least
, assuming the Voyager Probe series continued (which it didn't of course)
Unless Decker was just lousy at history?
(Why the Okudas put the V-6 launch in 1999 is anyone's guess)