Interview Question on Common App

Unfortunately, these last two weeks I have been swamped with work and so I had to postpone my CMU interview for January. This means that it will be after I submit the Common App. There is the one question on the Common App regarding the interview and why that contributed to your decision to apply. I want to inform them that I will be doing my interview after I submit the app, however, most websites and forums that I have visited have stated that you should just leave that box blank if you have not had an interview yet. I don’t want the admissions office to think that I am not having an interview at all especially when there are so many alumni in my area.

What did/would you guys do?

Thanks in advance!