For pub gigs we normally finish setting up and soundchecking around 30 seconds before we're due to start, so we look at our watches, say " right, let's start ", drummer counts in the first song, at which point one or both of our singers will decide they need to go to the loo/get a drink/sort out their lyrics/send an urgent text message, so the rest of us just stand there looking stupid until they've sorted themselves out, drummer counts us in again and off we go! Completely amateurish but no-one in the band apart from me and the drummer seems that bothered about it.