The main required courses, or "the core" classes, include the statistics (EPI 202-204) and epidemiology series (EPI 205-208).
You may take these concurrently in 1 year ("fast" track) or split them over 2 years ("slow" track) by focusing only on the epidemiology series first. Below are the recommended coursework timelines whether you take the core courses together or split.
To maintain being a full-time student, you need to register for at least 12 units per quarter.
MS and PhD students have to take the same core classes. However, if you choose the thesis track (Plan I) rather than the exam track (Plan II) as an MS student, you only have to take 9 units of electives in your AOI rather than 12 units.
MS students typically graduate in ~2 years. If you are done with all classes and nearly done with your thesis, it is possible to go on Filing Fee to finish up rather than still having to pay to be a student. If you are taking the exam track, aim to submit to Grad Studies (proposal and oral exam completed) by the end of the quarter you want to graduate.
It really depends on your preferences, as both tracks have their pros and cons.
Most students who have all the prerequisites completed (or who only have to take STA 108, which can be taken concurrently to EPI 202 Fall quarter) choose to take the "fast" track. The advantage of the "fast" track is that you can get almost all of your core classes done in 1 year. You also have to worry less about figuring out electives your first year, which is especially helpful since many don't have a Major Professor picked out yet to provide research units to meet full-time student status. Then, when you have a Major Professor and research topic picked out, you can take electives more tailored to your established interests. Another pro is that this allows you to take both sections of the Pre-QE the following summer (relevant to PhD students only).
However, by cramming all the core classes into 1 year, it leaves you less time to take electives or spend time thinking or talking to professors about your research. The core classes still require a lot of your time for homework and studying, despite being grad-level classes.
Students also frequently take the "slow" track instead, especially if they have multiple prerequisites to take that block them from taking the "fast" track. Focusing only on the epidemiology series your first-year allows you to take more electives, whether they be at the advanced undergraduate or graduate level (remember that undergraduate classes can often be stricter on grading). This is especially helpful if you are still figuring out your research interests, since it allows you to explore other topics and material outside of EPI. For these reasons, many MS students often follow the "slow" track. This track also allows you more time to meet with professors of interest to your research, whether you meet them through the electives or through cold-emailing. It can be nice taking classes outside of the EPI bubble as well. Splitting up the core classes does mean that you will also be splitting up the sections of the Pre-QE you take into 2 summers (relevant to PhD students only). This makes studying for them easier however, since you only have to study for the 2 epi written exams (basic and advanced epi) the first summer, and the 1 stats written exam the second summer.
Note that even though it is called the "slow" track, it does not necessarily feel slower, and your daily schedule will still likely be filled. Whether students take the "fast" or "slow" track, PhD students often still end up advancing to candidacy (taking their QE) around the same time.
Looking for electives to take can be tricky, especially since availability is different year-to-year. Some classes are only available every other year, while others get retired as professors move on to other things. Make sure to compare the list of Approved Electives on the Policies & Guidelines page of the GGE website with ScheduleBuilder to see which electives are available to take each quarter. It can also be helpful to reach out to other students to see what they are going to take, or what they have taken.
If there are any electives not listed in your AOI but that you feel would be relevant, you can also fill out the survey on the Policies & Guidelines page of the GGE website to get your elective approved.
Once you get a Major Professor, you will be able to sign up for research units under them to fill out your 12 unit requirement. Email the coordinator with your PI's name and say that you want to sign up for research units for EPI. The coordinator will provide you with a CRN to sign up.
In the meantime, you will have to keep taking electives to fill out your unit requirement.