as a qualified TD
Like your style.
Anyway, our rule is:
Free Entry Games - Players have until the end of the 2nd blind level to enter the tournament.
Cash Entry Games - Players are required to be Bought in (Paid For by someone) by the end of the 2nd blind level.
There are usually a couple of extra chip stacks at empty seats in play to allow for late arrivals until the end of the 1st blind level.
Players arriving during the 2nd blind level (after spare stacks are removed) will be chipped down 500 in tournament chips.
That's how we handle it. So players can turn up late, but are penalised. Cash games they can be later than free, as they are paid for, and no refunds given.