There are a number of factors that impact when you will be able to access to your courses in Moodle:
1. The course must exist in Moodle
Each semester, all Moodle courses are generated automatically 21 days prior to the course start date based on the Banner system records. At that point the Instructors will get access to the course. After they have prepared the class for their students they can make the course visible to the students. This means that you will not be able to see any courses in Moodle that are scheduled to start more than 21 days in the future because they have not been created in Moodle yet.
2. The course must have you listed on its roster
When you register for a course, there is a record created in SSIU (Banner) for your enrollment, but this is NOT instantly transferred to Moodle. The Banner system sends information to Moodle several times per day to synchronize enrollments, so new enrollments are pushed into Moodle each time the systems synchronize. This process is entirely automatic, and it can take some time. You should allow at least 1 working day after registering for a course before expecting to see that course in Moodle. In some cases, this may occur a bit quicker, but you should expect it to take approximately 1 day.
3. The course must be 'turned on' or made visible by the instructor
Instructors are responsible for 'turning on' or making the courses visible to their students, and with a few unique exceptions, they are the only people who are authorized to do so. If you are still unable to see a course in Moodle, it is within a few weeks of the start date, and you have been registered for more than 24 hours, the best thing to do is to ask your instructor when he or she will be making the course available to you.
NOTE: For online courses, instructors will generally make the course visible within a week of the start date. For face-to-face courses, faculty may choose whether to use a Moodle course or not, so it is always best to ask.