best way to secure credit card hold restaurant cancellations? day of or night before?

[collegejunkie]

i'm waiting for a few restaurant ressies to open up and i'm wondering about the ones that have a credit card guarantee. is it better to look/call the day before, when people would need to cancel to avoid the penalty, or to look the day of? will the cancellations be in the system the day before? is there a time that they need to be cancelled by?