Doing this is pretty simple. Just click on the blue edit button beside a course module.
On the next screen, you can set:
Number of Days Until This Item is Unlocked: This determines the number of days that a user has to wait to access the module, starting from the day that they start the course.
Make This Item Available On: Allows you to set a specific day when the module becomes accessible.
Time Required to Spend on Item: The number of seconds that a leaner must spend on a module before it is marked as completed.
Must be Successfully Completed to Continue Course: If this is enabled, a learner will not be able to complete a course until the module has been fully completed.
This Item Must be Passed/Completed to Continue Course: If this is enabled, a learner will not be able to start any module that comes after the current module until the current module is completed.