How do you remember appointments?

I'm contracting on 2 projects - 1 east coast (less demanding), 1 central time (more demanding). I'm west coast. Separate computers, separate emails for each. I've screwed up meeting times way too often when I tried to coordinate it all on one calendar. I finally had to start putting blocks of "unavailable" time on the MD project calendar so I don't miss critical things on the LD project. It's basically a clusterfuck and I screwed up and scheduled a haircut on a Thursday when I also had a meeting on MD, a Zoom jury selection interview (that thankfully got cancelled), and a therapy appointment. So I am reading all suggestions with full attention.