As you said we have already had time skip, and while I don't think we will continually skip through the 4 years, I do expect at least one skip after Xmas. That one skip may scoot us into spring. I don't think DPC would want to miss the opportunity for a spring break as it has been mentioned in game and would certainly be something unique to university experience. It has the added benefit of breaking up the monotony of yet another free roam campus party.
Xmas holiday is definite. Jill mentioned a skii trip or other wintertime holiday activities, so I expect DPC to take full advantage of it to give us a setting beyond the prison walls of B&R. Ending the game at Xmas just seems like too much of a cliffhanger. I get that there has to be some loose ends since we are not covering MC's full life story, but end of 1st year just seems like such a natural conclusion point that would transition rather well into the game's epilogue. Sage graduation, Quinn in jail, Bella in mental institution, Jill researching her goblin family tree, MC Shazbaing several babies with multiple girls before age 20, it all just fits.