According to Memory Alpha, she was there for 8 years, which doesn't exactly jive with Julian only being there for four.
Perhaps Crusher learned medicine at the Academy whereas Bashir learned it elsewhere beforehand?
There are two canon dialogue tidbits on medical academies: in DS9 "Rivals", a Starfleet Medical Academy is mentioned, while in VOY "Nothing Human", a Federation Medical Academy is. (Every other reference from Memory Alpha is completely noncanonical, mere speculation on how a random mention of an "Academy" should be interpreted when relating to the various medical heroes.) So possibly Crusher attended the former (as indicated on her "Conundrum" Okudagram), thus making her Starfleet studies longer, while Bashir attended the latter or neither.