Study for the classes you're in now, and build a solid foundation to start real board prep next year.
It's worth familiarizing yourself with First Aid, but any hardcore board prep first year isn't a good use of your time.
Some people use Firecracker for spaced repetition of topics you've learned so far-- for me, it was time-consuming and I did slightly better on my exams when I started ignoring it, but I may pick it up again as an OMS-2 and see if if I can pull it off.