I have
WNMHGB using the United Earth Stardate system since Starfleet was under UE command. At that time, each 1000 Stardates equals one Earth year which starts each cycle on Jan. 1. I put the end of
WNMHGB, Stardate 1313.8 on April 24, 2265. The year 2265 is to keep in line with 300 years in the future since the pilot was filmed in 1965.
Starfleet assumed command of Federation's space operations circa May 11, 2265 and reset the Stardate clock at 0000.0. Since both Starfleet command and the Federation council are still stationed on Earth, all Federation members agreed to use 1000 Stardates equals one Earth year but just have a different "zero" cycle date. They also issued new uniforms, etc., but details of the transition of UFP members’ ships/starbases/assets are still in committee. By Stardate 3030, the UFP transition of Starbases/Outposts is completed, and the final transition of Starships to the UFP is around Stardate 3130.
After refit, the Enterprise was relaunch on its 5YM on Stardate 1300 (Sept. 1, 2266). The first documented event was
Mudd's Women on Stardate 1329.1 (Sept. 10, 2266). The final recorded TOS mission is
All Our Yesterdays on Stardate 5943.7. Depending on where you put
Day of the Dove (Stardate unknown), it could be the last recorded mission based on Kang's "3 years" (3000 Stardates) comment which, if exact, puts this event around Stardate 6200. I prefer to put DOTD a little over ~2.5 years after
Errand of Mercy (~Stardate 3200)
. Kang must have been rounding up or just not exact with Earth year nomenclature. <edit. Or Kang is using Klingon years which are about 80% of an Earth year.

>
Normally, I don't bother with TAS, but if I did, I'd put the last three TAS episodes by Stardate just after the 5YM while the ship awaits its refit. Overall, Stardate order is not without problems, and there are four or five episodes where we must assume a script error. YMMV

.