In conducting an Event Impact analysis, one needs to look at:

The impact from the day the event takes place until it ends.

Only the event itself and about a week or so after as an event does not have long lasting effect.

Before, during, and after and there may also be smaller events that are co$-$located with the major event.

Only the event itself and a few days before the event as attendees may need to come early to set up their exhibits or perform other preparation work