I can only speak for UoP.
Interviews are conducted all the way through March so for the borderline applicants, they definitely do wait for fall grades. The academic dynamos, like Chebs, get the earliest interview invitations. That is to say, if the AdCom feels that they have enough information about your ability to make it through the academic portion of the schooling, then they extend the interview, sans grades.
I don't think UCSF's interview season ends in Dec either... but I am not an authority on that.