I take into consideration the place I'm going to and why. If it is an appointment I usually get there about 10 minutes early (I factor in traffic and parking in the area) for events like cookouts or parties it varies. If it is a good friend's event I go over early to help out and stay late to clean up if I can.
Thats a good way you decide when your getting somewhere i to Ike getting there a lot early if a friend is hosting to help with getting everything ready and I find that is always appreciated