A study plan has to be compiled from Poliself by selecting among the courses available from the application courses that satisfy the rules defined for each cycle. It can be updated in given time slots defined by the School. Any change in the study plan should be approved by the Tutor. Since she/he cannot know when you fill in or update the study plan, you should send a copy of it to your Tutor and forward the email approving it to the phd office (email@example.com).
Schedule of each course is available on the course description here, and also from the study plan application.
Once compiled the study plan, students have to send an e-mail to the respective Tutor asking for approval, which will be done through an application that he or she will access from the personal Politecnico's services home page.