It depends on how many items are in it, how often you study, how well you study, etc.
Previously you could master an item by cramming in just one month. Now achieving mastery of an item now means greater spacing in between quizzes. You attain mastery with less cumulative study time, but that time is spread out over a longer period.
Sometimes you may have to wait for months until a course becomes ready for study. If that happens, we recommend that you start a new course rather than just waiting.