This is designed to be a 4 month, cohorted program. You should sign up and pay for all of the courses within the 4 month window. Because the program is designed to be cohorted, and things like peer grading all happen within your cohort window. If a learner cannot complete their courses in 4 months, they may stay enrolled for the duration of 2 years after their original start date.
Note: If you are intending to enter the MSW program, this may delay your MSW program start date.