How do you define an event?

Something that happens is an event.

So usually there is a cause ( Subject )  , and action or an effect (object) , a time and a space. This forms the basis of all that is. Because everything is an event. From our ” breathing” to taking companies public in an IPO. Its all an event. 

But the funny thing is , in order for an event to occur , you must define time and space.

But what about the event called ” the definition of time and space” ? Who decided that , ” from henceforth Time and Space shall exist”?  What was before that definition?

How would you define that event, relative to reference points?