Our professors told us NOT to worry about it at all during our first year. You're learning so much about the foundational aspects of the profession that it's not really practical to study for the exam when you haven't covered half the material yet. They even told us not to worry about studying over this current summer (I will start my second year of the program in the fall - MSOT). In reality, from what I've heard, I don't think anyone really starts seriously studying until closer to the actual point of graduation. Over this current summer, I plan to 1) RELAX!, 2) read/re-read important parts of our Occupational Therapy for Physical Dysfunction book (which is a commonly used textbook in many OT programs), 3) brush up on Neuro, and 4) work a ton to make some money so when I am doing fieldwork next summer and can't work, I won't starve 😉 The one thing they did tell us to do was to keep a lot of our textbooks so we can use them to study for the NBCOT, and also to be able to reference during fieldwork.
If you want to keep tabs on the kind of questions, you can "like" the NBCOT Facebook page - every Monday, they post a review question for the OTR and the COTA exams, provide the answer choices a day or so later, and then the correct answer AND the rationale behind the wrong ones by the end of the week. It's a good way to build a little confidence when you can read the question and guess correctly, which I've been able to do even after this first year (not always, of course, but sometimes). However, they recently had an issue with people copying the questions and distributing them (and tried to fine the people who did it), so you are NOT allowed to copy and save them, even for personal use.