When you're in an interview, try your best to show that you care about the company and how you want to help it grow. Asking questions about promotions or continuously focusing on what you can get out of this job position may be off-putting to your interviewer. Questions about career progression should be asked after you get the job, and after you've been at the job for a good while. The best time to address the topic of promotion is usually during a performance review.
Remember, your interviewer has probably talked to a ton of job candidates, which means she pretty much knows what you're thinking when you ask questions with promotions in mind. She will know why you're asking her how long she's been at her position and how long it took for her to move up. Don't get me wrong, it's OK to bring it up briefly and with finesse, but you need to be really careful about how you phrase it. Be sure not to belabor the point and put less emphasis on what's in it for you, and more on what you can do for the company.