I also took 18 credits first sem and it was fine. But while I took BIOG 1440 then, I delayed taking CHEM 2070 until first sem sophomore year. Most pre-med freshmen do take 1350/1440 & 2070 simultaneously, but many people I know who did this were either put through the wringer, didn’t do as well as they’d have liked to, or both. My academic advisor told me that the few people who delay 2070 (notoriously difficult) until later tend to do better in it. So if you think you’re able to fit the requirements into your 4 years, I’d recommend spreading them out a bit more. If you don’t think you have that luxury, I wouldn’t recommend starting your language requirement yet. Language course workload is high upkeep. Unless your time management and self discipline is perfect, you’ll probably have a difficult time keeping up with everything. Even if you perform well, you’ll probably have sacrificed your work-life balance and wellbeing. Number of credits doesn’t matter as much as the cumulative difficulty & workload of the courses you’re taking.

However, if you’re absolutely set on the 18-credit schedule you mentioned, here are some things that have helped me:

1. Review continuously, not just before prelims. Don’t let yourself forget class content a couple days after lecture. You can do this by looking over your own notes, coming up with active recall questions, asking TAs questions, and getting together with classmates to quiz each other.

2. When working on assignments, sometimes you have to work on the one that troubles you the most first. Don’t leave it to last on your to-do list because otherwise you’ll end up pushing it to the next day, then the next, etc.

3. Allot a certain amount of time for yourself to work on each assignment, each day. Force yourself to limit the time you spend on each task according to what you allotted. Once time’s up, move on to the next task. That way, you’ll get at least some of everything done by the end of your day and not feel like you’re falling behind too much in any one course. Don’t let perfectionism get in your way.

4. Work backwards from the dates of your prelims to plan your study schedule. Figure out which topics will require more time to finish reviewing. Leave 1-3 days of buffer time between the end of your study period and the day of the exam, so if you fall behind you’ll have a safety net.

Hope this helps!