January 25, 2015 Deadline to apply to graduate (through ACES).
March 19, 2015 (or 2 weeks before your scheduled defense) Deadline for “initial submission” of dissertation. Then they e-mail you to tell you what is wrong with your formatting, and then you meet with someone to work it out.
Somewhere in this time frame, your adviser has to send the grad school a letter that you are ready to defend, and your department has to send a “defense announcement.” Then you have to physically go to the grad school and pick up your “examination certificate.”
April 6, 2015 Deadline to defend dissertation (this is earlier than I thought).
April 20, 2015 Deadline to submit final dissertation and “exam card” to the grad school.
But I am not liable for any errors here. Check out http://gradschool.duke.edu/academics/preparing .