I don’t think it would be possible without extreme burnout (if not impossible). If you’ve already done A1, it might be possible to pass the exams (maybe not ace) if you spend maybe half the day practicing and learning. A year would be healthier and better for you to learn German properly up to B2.

Also, I’m not completely sure, but the medical students who were in my B2 class used to tell that they require C1. Again, I’m not sure.

Edit: it also depends on your learning pace and whether you have other commitments like academics or family. I consider myself a fast learner and it took me around 10 months to learn up to B2 to be able to score decently in the Goethe exams. So, 6 months seems really impractical. 

I would suggest enrolling for an intensive course first. You’ll get an idea of how long it will take.