I just heard feedback from one of the admissions personnel. Invitations were sent via email on Feb 28th - with the first round of interviews starting next week. Unfortunately, if you haven't received anything by now, it is unlikely that you have been invited for an interview and correspondence on official acceptance/rejection will be sent out after interviews are completed. I myself didn't get an invitation to interview - so I'm pretty bummed since Georgetown was my first choice! But hope this information puts everyone at ease. Good luck on other applications!