<p>Depends on the department. I got a financial offer alongside the decision (physics). See thegradcafe or similar sites if you want to know when a particular department starts responding.</p>
It varies entirely by department. Some departments notify earlier than others, although I imagine most acceptance notifications will be sent by the end of February.</p>
<p>According to that obviously, they send out acceptances in waves. My friend, for instance, has not heard back yet, but February end sounds very on the money.</p>