How long does it take to have a anniversary?

Answer 1

No time at all. An anniversary marks the point exactly one or more years after an event. For example, many countries mark the anniversary of the end of the first world war at 11:00 a.m. on the 11th of November, 1918. The anniversary takes place exactly at 11:00; 11:00:01 is one second too late. However, the celebration of the anniversary can take as much or as little time as you like. Most people celebrate anniversaries of people's birth (their birthdays) for one day.