You can find all the information related to the start date and the course duration on the course page, Course Schedule section, in your student account.

The courses are 8 to 12 weeks long and consist of about 5-12 modules. Every module, depending on the course, is activated with a periodicity between one and two weeks. 

You will be able to see and access only the active modules. You have to wait until the next module is allocated. 

Previous modules can be accessed any time until the end of the course.