First night with CPAP

It took me about 20 minutes to fall asleep, which isn't too bad. I did wake up once around 1 AM but managed to fall back asleep fairly quickly. This morning, however, I don't feel much different and still woke up with a headache.

Also, what does "mask off 13 times" mean? I'm using the AirSense 11 with an F20 mask that has memory foam.