August is traditionally slow and September through the holidays has always been a busy time. Most people are still vacationing including Realtors during August. The annual MD Realtors convention is September 9 to the 11th and after the 11th things pick-up. I have a friend in the Hopkins HR department and he thinks and I would agree the best way to reach incoming faculty is through craigslist.com postings. We advertise on 25+ websites and find a lot of Hopkins clients via our craigslist postings.
We've also advertised properties in the Student newspaper: http://www.jhu.edu/gazette