Please contact your advisor as soon as you realize you cannot make it. While it is not an ideal scenario, canceling at the last minute is better than being absent without explanation. Your appointment time is reserved just for you. An advisor who knows you are not coming may be able to help another student at that time. There is a rescheduling option in the online scheduling system. Access your confirmation email for the link to reschedule. If you are more than 15 minutes late, your appointment will be marked as a "no show." Accidents happen, but you should avoid having a "no show" in your advising life.