If I say I will be there at x time, just add 30 minutes MINIMUM. Even with business meetings, I don't give a fuck, count on it.
But you best be on time. My life is too interesting and important to wait on your behalf.
Matter of fact, this one girl once made me wait a little bit, so I called up another chick who didn't hesitate and met me within 10 minutes.
Needless to say, when, let's call her Julia finally got there, I was already face deep with prompt chick. True fucking story.
Call me selfish, guess what, I am. If you aren't steamrolling others, you are misunderstanding what it means to be successful.