iDefensiveDriving.com will allow you 120 days to complete the course.  If you have not completed the course in 120 days from the day you registered, your account and course information will automatically be cancelled.

However, the most important time limit you must consider is the one your court gives you, which is usually shorter than the 120 days we allow.  Make sure you know when your course completion certificate is due according to the court.