While this question seems about as straightforward as it gets, hiring managers aren't solely concerned with a date on the calendar. They're testing your willingness to be loyal to your employer, or any employer, by giving proper notice. Don't be too anxious to start right away, or fall into the trap of fearing that an answer that isn't immediate will result in a missed opportunity. Express your commitment to integrity and honesty to any employer, and realistically lay out a timeline for proper notice.
