This question is somehow difficult to answer, but if you are ready to start on this journey you mosly like to have an idea. First of all do you have any experience in learning a foreign language?
I've just asked because once you have learned a Foreign language, you will have a better understanding of the overall language learning and each new language will be easier than the last.
Let's suppose you've never tried a new one. Well, it might take you longer but it doesn't mean you can't learn.
Let's go back to the question how long does it take to learn this beautiful language fluently?
Every brain works different:) but you will need to have these two keys; discipline and determination. Do you? If you really do you'll speak French in a short amount of time.