Why do people ask this question?
I think people, who are non-native speakers of English, who ask that question are looking for a magic pill. They are looking for a solution outside of themselves. If they take this course, or if they study with that tutor, or if they use a certain app, or if they pay a certain amount of money then–SHAZZAM–they will speak English fluently. Truth be told, the degree to which you learn a language depends on how much time and attention you give the language and how much you believe that you can achieve your goal.
When people ask me how long it will take, I ask them how long it took to learn their first language. It will probably take themabout the same amount of time to learn English as it took to learn their mother tongue. [continue on my website]
http://englishvoicetovoice.com/how-long-does-it-take-to-learn-english/