Similar to the core courses you do not have to enroll to your elective courses via Osiris, Canvas or SIN-Online. The course enrolments are automatically processed per block, after each switch period, by Programme Management.
Once the course enrolments are processed in Osiris the course will automatically appear in your timetable. If you would like to know the course schedule before the official enrolments are processed, you can check the schedule via the course catalog.