Spring semester does indeed begin in January, so depending on how long Episode 12 is we might see Zoey join B&R. I doubt it though, it's usually like mid-January.
That's something I don't like about Season 3, the pacing. It feels like only a couple days pass, similar to Season 1, but in reality we burn through a few weeks and only see a sliver of it—even less, in Episode 9's case. And because of the party planning minigame, we cannot proceed past NYE in any meaningful way, Episode 12 will more than likely be the final weeks of December at most.
Season 4 will probably be even more fucked, especially since we likely will not get a full 4 episodes.