If you're on disability for a mental disorder the normal cdr schedule would be once every 3 years, however ss is backlogged and often it will take longer to receive one. Depending on what you're approved for cdr's occur every 18 months, 3 years, and 7 years. No matter what your disabled for if you're under retirement age you will get one or more cdr's. The cdr is based on the past 12 months of medical notes only. The length of time will vary. It could be several weeks to several months.