I use my phone. Set up widgets on your homescreen so you can have instant access to your calendar. It's worked wonders for me. Bonus points if you have a tablet where you can explore the monthly view by touch.

I just use an online calendar, or braille. If you prefer handwritten calendars, maybe try using a sharpie and write a lot bigger.

If you have enough sight to handwrite and to *sometimes* be able to read your own writing back, I highly recommend an iPad + Apple Pencil, it completely changed my life as a VI student. I have a full hyperlinked academic planner on GoodNotes that I can handwrite into and zoom into to reread what I wrote. Also super useful for quick handwritten notes, drawings, diagrams, annotating papers, doing readings, keeping textbooks etc. Anything a sighted person would do on paper.