The instrument-written test is good for 24 months. After passing your exam, your certificate for the instrument written test is valid for 24 months. Within these 24 months, you must complete your IFR training and pass your check-ride. Twenty-four months is adequate to complete IFR flight training and pass the check-ride. Failure to complete your instrument rating training or, unfortunately, not passing your instrument rating check-ride within 24 months will require you to retake the instrument rating exam. You may need an updated IFR written test prep to practice for the instrument rating knowledge test. The FAA updates its question bank frequently, and the questions you practiced for two years may not be relevant to the problems today. Instead of waiting for 24 months to get your IFR rating, allocate some time and try to complete instrument rating training in a few months.