That means ten to fifteen minutes early. Sometimes, interviewers are ready before the appointed time. Using a person's name personalizes the conversation and adds warmth. If you don't know the name, call the switchboard beforehand and ask. Also get the secretary's name so if you need to call back, you can use it.
Secretaries can have some potent influence.
Demonstrates you are prepared. Don't jump right in and get down to business. Get comfortable with each other. Whatever time you invest will be repaid tenfold, for personal chemistry is a main ingredient in the hiring process. If you like you, the rest of the interview will go well.