I can't honestly remember how long it took. Not that long, possibly. The first book took a while, but at the end of the book I had decoded what I first didn't understand (by seeing the words used in various contexts), and reading books after that became easy. New expressions and phrases were quickly understood.

Before that I had been reading a magazine about stuff I was very interested in (I for one need more motivation than just 'learn the language'. I believe my interest in what I was reading was crucial, without that it wouldn't have worked).

Then I read a couple of relatively short books about science, again not too difficult. At a later time I picked up a book in the international section in a book shop while travelling for work (lots of hotel time..), and since then I just continued.

And yes I think it does help a lot with my speaking proficiency too (I think that was what you meant by your last question), although it does absolutely nothing for my pronunciation..