Got to concur with the last post.
Mine took 10 1/2 months from opening the first book to sitting my final exams. It can be done much quicker, but I would suggest that it would need to be full time study, whereas my study time was split with 40 hours per week full time employment, working shifts and a young family.
As a slight calming of the nerves, some of the subjects have extensive overlaps, particularly areas like radio nav and instruments, so this means there is slightly less to learn than first appears (admitedly only about 10%).
Regards,
Obs