To folks still holding out on declining their offers-- If you wait until the last day to decline, the school likely will not be able to offer that spot to someone on their waitlist (even if your decline then triggers room to do so) due to administrative deadlines. Typically, all offer acceptances (waitlist and regular) must be made by a certain date. But if you decline sooner, you are giving the school enough time to turn to their waitlist, and you're giving someone else a shot!