So since I'm on birth control, my period is pretty regular. It always comes the Thursday after I take out my Nuvaring. It used to come early in the morning but then last month it came late at night. This morning I woke up, got ready for work and debated putting in my cup, but then figured "nah, what if it comes later this evening, like last time?" and just wore a cloth liner.
I got to work, and not even an hour later I realized that, yup, period had started. Awesome. By the time I managed to get another break to change my liner into a thicker cloth pad (that I had brought "just in case") I had soaked through the liner and was feeling generally icky. Even though this is only my second cycle using the cup, I'm definitely not a pad person anymore!
It was such a relief when work was over and I got to put in my cup! And I've learned my lesson... next time I'm putting the cup in the morning of my period (because seriously, even if it wouldn't have come til the evening, it would've been perfectly fine in all day)!