Courses are created after the registration period for the upcoming semester - roughly late November and late April. They are created as hidden from students so that you can organize your materials as you want them before allowing students to view.
Undergraduate students are automatically enrolled in Moodle courses through a synchronisation between MyJCU and Moodle that takes place twice a day. There might be delays (no longer than 12 hours) in the update during drop-and-add periods because of this. Graduate students and continuing education students are enrolled manually by the Moodle support team as soon as they receive the lists; any update depends on communication from the dedicated department to the Moodle support team.