It will help to focus on the problem eight weeks at a time. Look into your calendar for those first eight weeks. Block out any holidays and prior whole-day non-work commitments (if any). Resolve to write every remaining weekday for at least 30 minutes and at most 3 hours. (You should never write for a whole day.) Book these sessions into your calendar. In an ideal world you would book 40 three-hour sessions from, say, 9:00 to noon. But you'll probably have to settle for about 30 or 35 sessions, many of which will only last 30 minutes.
How many hours of writing time does that give you? How much do you realistically think you can accomplish in that time? Set some writing goals on that basis. Then break those goals up into smaller tasks ("things to do") and assign those tasks time in your calendar. Be as a specific as possible about what you will be writing on a particular day.
Try to be realistic. If you need time for "free writing" or "thought writing" (writing to find out what you think) book that into your calendar as well, but the important part of the challenge is to find time to write down what you already know needs to be written. If you don't yet know what you're going to say this semester, then your challenge is, in part, to figure that out. But you should still find at least 30 minutes a day to write down something you know you want to say. Keep in mind that we are only talking about eight weeks in the very near future. Surely you know something about what you have to get down on paper.
Now, remember that you're working on what could ideally be a 40-paragraph text. An article-sized statement of what you know. Conceive of your plan as a schedule for working for 30-minutes at a time on those forty paragraphs. You are of course allowed to work on a paragraph more than once.
Assuming that you do have something say, then, here's the challenge: write always and only when (and what) your calendar tells you to. Don't write when "inspired" to do so (unless this happens to coincide with your writing schedule) and do everything possible to keep your appointments with yourself (the writer). Make a plan, always for 30 minutes & one paragraph at a time, and resolve to stick to it. Learn how to take a moment.
At the end of the eight weeks, add up all the writing time you did. How well does it compare to the between 20 and 120 hours you planned to write (between one half and three hours a day for forty days)? Now make a plan for the next eight-week period, try to make it more realistic than the last. Take a break (either a one-week mid-semester "reading" break or a Christmas or summer holiday). Then get back to work.