It's important to consider that with online coursework, required readings need to be completed and lectures viewed before you begin taking part in the weekly discussion boards. Online learning requires good time management throughout each semester.
For each 3-credit course you take, you can estimate an average of 8-10 hours per week for required readings, online discussions and assignments. Some weeks will be heavier when assignments are due in addition to your weekly lectures, readings, and discussion board engagement. This means as a full-time student with 2-3 courses you may have up to 30 hours of academic work each week.