I think the main goal of the first year (well...every year of medical school really...) is to be the best student you can be! Consistent hard work and diligent studying for your classes early on is something that can really help you in medical school, especially when prepping for the steps.
If your school lets you take subject shelf exams, I highly recommend buying subject specific review books, so that you may use them when the time comes for step 1 prep. Fortunately, my school lets us take NBME subject shelf exams, and I thought these were a good way to gauge how well I learned a subject and what I had to improve to be "up to snuff" for Step 1.
I think it would be most helpful if you focused on class work/shelf exams for now and started considering step 1 preparation during the second semester of MS2 (assuming you take Step 1 after MS2). All the preparation you do now for your classes will pay off for Step 1, trust me!
Good luck!