I really can't give you an idea of how long it takes, but I do know most of the lawyers who have immigration practices and are dealing with the question of when a good start would be for their appointment are cognizant of that period of time. It really depends on their own knowledge of the situation. So I can imagine that if you're a lawyer in Toronto you would get a flavour for whether or not you had some colleagues who would be willing to move into your practice and move quickly, but maybe if you work in a more isolated community it would take you longer.
On March 12th, 2008. See this statement in context.