In many ways, learning online is similar to learning in a classroom. Your instructor will provide quality readings, exercises, assignments and quizzes. Like in person classes, what you get out of it is a result of how much you put into it. Expect to spend the same amount of time and energy on an online class as you would in an in person course. In fact, for some students online classes can take more time and energy than in person classes.
On the first day of the term your instructor will expect you to log in and participate. The Academic Calendar contains all important college dates you should know including the dates for the start of terms. It typically doesn't matter what time of day you interact with your online classes this first day. Just be sure to check for assignments, activities and participation requirements that are due during the first week so the instructor knows you intend to take the class.
Beyond the first day of class it will be up to you to decide when you want to log in and work on your assignments. Most online classes will have specific deadlines for quizzes and assignment. Due dates for course requirements will be listed in a syllabus or course calendar. Successful online students will log in several times a week to check for updates to their classes, participate in online discussions, and work on assignments.