The interviewer needs to know that they can count on you to be at work at your assigned time every day. Assure the interviewer that you are a punctual person, and you are always a couple of minutes early when arriving at work. Be sure to mention that you plan for traffic, and if you live somewhere with snow, be sure to say that you watch the weather ensuring you leave enough time to clean off your car and drive a little more cautiously when necessary. If you have children, be sure to mention that you have backup plans in place for childcare should something fall through with your typical plans.
"I was raised by the old adage that if you are not 10 minutes early, you are late! I always give myself ample time to make up for traffic or other unforeseen circumstances. Rest assured, if you hired me, you would be bringing on a very responsible team member."