I've had to cancel 4 times. I like to schedule about 2 weeks in advance. 3 times was because of work and the other time I had something come up. The time I canceled for personal issues, I rescheduled for just 2 days later. My work cancellations required me leaving town for 2 - 3 weeks, but I saw 2 of those ladies immediately upon my return. I gave 3 of these ladies at least 3 days notice as well.
The only reason I didn't reschedule with the 4th lady was because she gave me such a hard when I canceled. We exchanged several emails talking and setting up a date, she had given 2 days/times that would work for both of us and asked me to choose one. I responded with an answer, then never heard from her again until the night before (4 days later is when she actually sent me the confirmation email) our meeting. However, we were previously communicating through P411, and for some reason she sent this last communication directly from her personal email. It went to my junk folder, so I didn't see it until I was at work the morning of the appointment. At that point, there was no way I could leave work since I had never made any plans to do so. She wanted me to pay her full donation amount. No way I would do so since I thought her delay answering and change of communication form were the main reasons it didn't happen.
My point is this: If we bother to contact you (a provider) and go through the entire screening process with our personal info, then obviously we want to see you. If you just act professionally if I have to cancel, I will be rescheduling as soon as I can.