I was amused to read that the late, great Elizabeth Taylor had it stipulated in her will that she would be fashionably late to her own funeral. Sure enough, pallbearers did not carry her casket into the service until 15 minutes after it was scheduled to start. Classic!
Of course, for the rest us, punctuality is always key. In fact, the only social situation in which I find it acceptable to be fashionably late (besides your funeral, of course, should you choose to follow Liz’s example) is a party in which guests flow in and out as the evening progresses.
A dinner party, however, is a different matter. In these cases, it’s usually best to arrive on time (not early, in case the host or hostess is scrambling to prepare) or no more than 5 minutes late. Any delay longer than that and you should alert your host as soon as possible. Dinner parties require a lot of careful timing and preparation and you want to be considerate so that you get another invite!
A hairstylist friend of mine also suggested I remind people that stylists (and other service professionals, from your dentist to the restaurant where you made dinner reservations to your favorite masseuse) are busy people too! Showing up more than 5 or 10 minutes late can throw their entire schedule off, delaying services for other clients who did bother to turn up on time. If you are going to be late, call and ask if you should rebook (though realize that some places may charge a cancellation fee). If they are able to squeeze you in, give them a bigger tip as a show of gratitude.
Never lose sight of the fact that being on time shows respect for the people you are meeting, as well as signalling a responsible and capable image. If you have to, set your watch and the clocks on your mobile devices a few minutes ahead so that you trick yourself into leaving early.