...That's assuming that a stardate year begins in January. But Paramount seasons begin at the end of the summer, and the few times we do hear Earth holidays mentioned, they don't seem to fall on their proper places if SD XX001=January 1st is assumed. Rather, they fall more or less on the places they hold in a Paramount season, for obvious reasons (that is, an episode mentioning the Hindu Festival of Lights is aired around the time of said festival, in autumn - towards the beginning of the stardate year rather than towards its end).
As for the original question, it seems the fleet takes but one day to cross from Bajor to Cardassia, in accordance with earlier such crossings. The battle is probably over in a matter of hours. So our heroes could well be back at Vic's within just three days of their original departure, of which merely the "return trip day" would involve Winn and Dukat camping in the caves. Not a major continuity problem, then. But I, too, like to think that it took some preparing after Worf and Ezri's triumphant return and whatnot before the final invasion was launched; anything is possible, including the series-concluding episode actually taking place past the season border, that is, well into the next stardate year. Stardates and seasons didn't synch in early VOY, either, suggesting a season need not describe a full year or vice versa. (And let's remember that TOS gave us about 5,000 stardates and a supposed five-year mission, all in three seasons..)