Structuring Your Online Course in Moodle
With Modules, you may want to enable the "completion tracking" feature in Moodle to direct students' progression through the course by setting prerequisites. You can also set completion parameters that restrict students from leaving a module until all defined activities are completed or pages viewed. This course is set up with these limits so you can experience how it works. Contact the Online Education Dept on how to use this feature in Moodle. Go to this website to learn how to use this feature: http://docs.moodle.org/25/en/Tracking_progress
You do want to set the dates for each module/unit/week to open. You want the class working through the modules together, learning with each other. (If you do open all the modules at once, you will have students who finish in record time, but miss all the interaction with you and their fellow students.)
In summary...
Your course instructions should make it clear for your students how to progress through your course, as well as the important deadlines they must meet. Under the Activities block, Moodle automatically generates an ordered, dated list of all the Assignments. Moodle also adds all assignments to the calendar for you and is listed under the Upcoming Events block. Very handy.