fashionably late

Depending on the type/style of the event fashionably late can also range from 5 minutes (to a dinner date or a small gathering) to 45 minutes-1 hour (21st parties please note that there are also varying categories of 21st parties and discretionary judgement must be exercised). This time frame, or 'cushion', allows enough other people to have already arrived so that it is not only the birthday person and their parents in attendance and also conveys the possibility that you have come from a previous engagement (please refer to above definition).