This is an important factor that usually sets the professional apart from the amateurs. ALWAYS have a written contract for services with your DJ (or any vendor) stating the exact date, time and location of your event to ensure that your DJ will show up, be ready on time at the right location. Other details should be stated and agreed upon in writing as well to avoid miscommunication or misunderstandings associated with your wedding reception plans. A written contract is a legal and binding agreement for both parties to guarantee the event to be performed. A verbal agreement allows the amateur to back out of the agreement under the terms of a misunderstanding or miscommunication. The amateur DJ forgets, never shows up or remembers at the last moment when he has made other plans. A professional never forgets and by using a written contract shows his serious intent to perform as you are expecting.