How long do you wait for a date to show up?

The other day, I was going to meet a first date for dinner.  15 minutes after the scheduled meeting time and no date, I started to worry that she might be a no show.  So, I started reviewing the menu in earnest.

When a half hour had passed I went ahead and ordered.  I figure that everyone can be running a little but after a half hour, I have to assume that something major has happened.

It was a bit awkward eating by myself, but I am a big boy and can deal with it.