Don't think there are any set rules on applying to starting timesclaes, it all depends how quick you can get through stages, and also how many people are holding, which in turn depends on how many people the college is currently taking in each course.
I applied last April, and took the stages at a fairly steady pace (due to other commitments), I was told i was succesful in August, and at the time was offered September course, although I chose the January course.
I was then deffered from the January course onto April, due to the college cutting back on the January intake. So when i start in April it will be almost a year.
That said, I'm sure way back in this thread there was someone that did it in something like under 3 months!!