The length of time between promotions will vary depending on the length of time it takes each student to learn the required curriculum for each level.
One of the things that we recognize at Enso Center is that people progress at their own speed. In general, this occurs every 3 months but varies from person to person and at different levels.
As your rank increases, so do the requirements and expectations and consequently the time between promotion tests will be longer.
A key factor in the time taken is your diligence in practice and how often you are able to attend class.