fatpad,
I actually cancelled my interview on Jan 10th after my last message on Dec 10th.
The secretary actually went ahead and gave me a spot on january 15th a few days later.
If I cancel an interview I usually do about a month before theh date, so no worries there.
I would be pretty annoyed to if people were cancelling interviews within a week or days before, b/c the more likely those spots would not fill.