Your dissertation defense could be scheduled as early as the end of your fifth year, though it is more customary to be held at the end of your sixth year. An “Intention to Receive Degree” form must be filed prior to scheduling the defense. Be sure to schedule your defense well in advance, and work with the DGSA to make sure that everything is in order well before the date approaches.
As per the Graduate School requirements:
[o]ne month before the dissertation is presented and no later than January 25 for a May commencement, June 15 for a September degree, and October 15 for a December degree, students must apply for graduation electronically by following the appropriate procedure in their student account on DukeHub. This application indicates the title of the dissertation, which must be approved by both the DGS of the student’s degree program and the professor who directs the dissertation.
[t]he dissertation must be completed to the satisfaction of the professor who directs the dissertation (dissertation advisor), members of the student’s milestone committee, and the academic dean of The Graduate School. The dissertation advisor must examine and approve that the dissertation is ready for defense prior to submission to The Graduate School, as indicated by a letter to The Graduate School stating this approval. An electronic copy of the approved dissertation must be uploaded to ProQuest for review and approval by The Graduate School at least two weeks prior to the defense. Deadlines for dissertation submission are posted on The Graduate School website and must be respected if the student wishes to receive the degree in the semester when the intention to graduate has been formally declared; if the deadlines are missed, the student must register and reapply to graduate in a subsequent term, and pay continuation tuition accordingly. Final doctoral dissertations are scholarly products of Duke University, and must become publicly available for reading, though they may be embargoed for a specified period before becoming publicly accessible. Dissertations must be submitted electronically to ProQuest in Ann Arbor, Michigan, and to DukeSpace in the Duke Libraries, where they are openly accessible online after any embargo. See The Graduate School/ Academics/Theses and Dissertations website for information about electronic submission and about procedures for obtaining a copyright, and the possibility of a temporary embargo before public accessibility. Abstracts are published in Dissertation Abstracts International.
See the corresponding “Bulletin of Duke University: The Graduate School” at: https://registrar.duke.edu/university-bulletins/graduate-school
Note that these regulations cannot be changed by the DGS or the dissertation advisor. All students are required to familiarize themselves with this process well before they intend to submit their dissertation. Students should note that these rules include detailed instructions on layout, footnotes, and citation techniques for the dissertation and the rules governing this process, found in the Guide for Electronic Submission of Theses and Dissertations (The Graduate School/Academics/Theses and Dissertations website: https://gradschool.duke.edu/academics/theses-and-dissertations).