A 'Meeting Start Time' is seen by most in the commercial world as a very flexible guide-line. Those from more rigorous professions-such as ex-marines-who join an organisation are staggered by the lateness of many and the consequent non-effectiveness of the gathering traditionally called a meeting. Why are people late? Because (1) lack of leadership allows them to get away with it (2) they are not aware of time, being too stunned and trance-induced by e-mail (3) They couldn't get out of a conference call which was running late.
It's easy, though. Start on time. Whatever. Even if initially you're talking to yourself. People will learn.