Last year, none of us heard until February 15. However, according to the admissions website, it will be a bit later this year:
Our online Summer Seminar application opens on December 1 and closes on January 31 each year. We do not make rolling selections. Selection for this program will be after the close of the application period with notification via e-mail to all students of either Selected or Non-Selected by March 6th.
This was the same message as last year, except last year, it was February 15th. When they say they do not make rolling selections and that you'll hear by March 6th, if it's anything like last year, you will wake up on the morning of March 6th with a message of either selected or non-selected in the portal. That's how it was last year. No one heard anything until the 15th. Best of luck to you DD. I know the waiting isn't fun (just wait til next year when she applies, though-it's even worse!), but hopefully there is good news at the end of the wait!