This article is from the Unicycling FAQ, by Beirne Konarski with numerous contributions by others.
There is a wide variation in athletic fitness, balance perception, and
reaction time among those learning to ride a unicycle. So it is difficult to
predict roughly how many hours it will take to learn certain unicycling
skills. An experienced unicycling instructor may be able to make a good
guess after watching someone ride, but it is impossible without first seeing
the rider in action.
It has taken people as short as 15 min. and as long as 6 months to learn to
ride. However, it generally takes 2-6 weeks of regular practice to learn to
ride and a few more weeks to learn to do turns.
Ken Fuchs - firstname.lastname@example.org
A good rule of thumb is that it will take about one week for every day it
took you to learn to ride a bike.