Memory Alpha also suggests Tasha graduated from the academy and was posted directly as LT with the enterprise as her first post.
Umm, how so? Picard in "Legacy" was said to have asked for the transfer of Yar to the E-D from her current Starfleet assignment, not from the Academy; it was said Yar's previous CO, the skipper of the ship where Yar was said to have served at the time, owed Picard a favor.
We don't know Yar's rank at the time of the transfer, but we next see Yar coming aboard the E-D in the "All Good Things..." flashback with full Lt pips on her collar. Supposedly, she was serving on the previous ship in 2363, then, having had plenty of time to complete her Academy studies (for which there of course is no "Conundrum" derived date, because the character was dead by then).
Memory Alpha jumps to conclusions on many things, but it doesn't appear to suggest the direct Academy-to-Lt-and-E-D thing at all.