With my friends and family that are like that I usually either tell them to be there 30 min earlier than required or call them when they should be leaving their house to make sure they are leaving on time. After a while they get the hint not to be late around me.
my wife is one of those always late people. i tell her th only thing she will be on time for is the funeral. she just laughs and says don't bet on it. everyone knows she is gonna be late, so we plan things earlier than we need to. it works sometimes.
I just don't worry about it... some people are always going to be late, some are going to be right on time, some are always going to be early. It's life...
I'm constantly calling my friend Daryl out on being late.