If your program is affiliated with a university, you should reach out to the Office of Enrollment or Admissions. They usually have a designated official that handles scholarships and veterans benefits. They'll want to see the COE as well as a signed letter of good standing from your program director stating your expected "clock hours" (AKA work hours). This letter needs to be resubmitted prior to each semester that you seek to utilize benefits.
Also FYI, if you are using chapter 30, keep in mind that when those 36 months have been exhausted, you can apply for an additional 12 months of chapter 33. In case you have a 4th year of residency or a year of fellowship. Could come in handy.