The progression of belt ranks is based on combination of factors, including technical skill, knowledge of Judo principles, personal growth and time in grade (attendance).  Your instructor and the technical director will determine your readiness for the next belt.  You will then be requested to undergo a formal grading, gradings are held 3 times per year.  The average time in grade for the lower belts is 6 months to a year, for ages 6 and under it could be longer.  Black Belts grading are conducted by the Judo Ontario Provincial Grading Board under the recommendation of the club technical director.