Short of any quality issues, QC seems to commonly go through on the day it starts, along with the testing phase, although this can go on over night too. I would say once you are in QC, you can look forward to seeing you shiny PC soon(TM)
QC is just a final check that everyting is spot on, pretty much a formality unless someone made a mess of something, but really it should get straight through that stage and be out for delivery next working day.