<p>Like everything else with this process, when to take prereqs is a variable thing. Some majors (like bio, biochem, etc.) have most if not all of the med school prereqs as required lower division courses for the major that you need to complete before taking upper division courses. If this is the case, you’ll be squeezing them all in the first 1.5-2 years. </p>
<p>If not, you can spread them out, and I would definitely recommend doing so in order to devote as much time to the courses as you need to do well. Remember that this is a numbers game, so try to get the best grades (esp in the prereqs) that you can. If the labs are separate classes, you can put those off as long as you want since they don’t give you any material needed for the MCAT - I didn’t take the labs until my last quarter of college.</p>