It completely depends on your personal motivation and willingness to study.
You should be able to finish the program in 6 months...no problem....including your instructor ratings.
I came hear with 0 hours and am almost half-way through my instrument in about 6-7 weeks.....that includes SEL & MEL private.
I take the training very seriously and want to finish in as little time as possible. That being said, there is a limit to how fast you want to do this.....after all, too much cramming of information is a sure way to not remember anything!
If you are serious about flying for a living you must balance the speed at which you learn with the retention of information.
My personal goal is to go from nothing to all instructor ratings in 6 months tops! If I go over, no big deal, this is just an arbitrary date. I'd much rather understand all material than breeze through it and then struggle in the end.
Of course, there are those who take less time, and those who take more.....many variable come into play. 6 months is an acceptable average.
Hope it helps.