Before actual interview, there is an orientation session. (It continues even after actual interview, but it's shorter!)
I remember Dr. McManus told "us"
1. Don't send e-mail or make a phone call to ask application status before December
2. Don't send thank-you card or e-mail
and, I also remember it's because there are tremendous numbers of applications.
As I was a bit nervous, I was not for sure about this. So, I talked with another guy (from Michigan & have interview on the same date), and we agreed that Dr. McManus had mentioned not to send thank-you card.
So, I didn't send it.
However, I believe the evaulation of our interview is already completed. Only should we wait until December.
I don't believe your thank-you card will hurt you.
Btw, I didn't get the name card of my interviewer!