I loved Nicholas Bates’ post on Presentation Tips : Start on Time, quite obvious, but easy to forget:
Start on time to reward those who turn up on time, to be able to manage your schedule and because it might be impossible to wait for everybody. But how do you cope with the problem of latecomers missing part of your message? Offer 100% value from the start but ensure that it is not integral to your argument until say 5/10 minutes in. Then ‘on-timers’ are rewarded with extra ideas. You get into the flow. And late-comers have enough to pick up the story. Start on time.