I applied through my school's career center and received an email the next day to set up a phone interview. I interviewed one week later; there were no unexpected questions. The interviewer was cordial, and she said that all decisions for next round interviews would be sent out by end of day.
I got an email around 4PM that day saying I didn't make it to the next round. Not sure what I did wrong during the interview as I thought it went well, but I do appreciate BCG's hiring team and their efficiency.