Answered by Stephanie, Hiring Expert at AT&T Inc., on Monday, February 9, 2015
An interviewer can’t know that you’re the right candidate in 15 seconds, however he or she could feel like they know you’re *not* the right candidate in that amount of time. Meaning, it’s easy to blow it early on by dressing inappropriately, being late, not being prepared with copies of your resume, failing to exude energy and interest, and overall portraying mannerisms that are not a match for the job. Assuming you’ve mastered all of those points, it should take the entire interview length (plus several more interviews in some cases) to evaluate your qualifications against other good candidates. So be confident, dress appropriately, smile, shake hands, have copies of your resume, and be on time, and you will have earned the attention of the interviewer for the length of the meeting.