This is the best course of action for the following reasons:
1. To gain a thorough understanding of where the DJ equipment is to be set up.
2. To verify the reliability of electrical outlets (proper grounding) for set up to eliminate the risk of equipment damage.
3. To draw a picture of how the reception will be set up from a sound standpoint.
Never ever is this MORE important than travelling out of your normal local area. I booked "Brie & Heath" back in February for their August 3rd wedding.