I agree with all of the comments here. So basically it depends on your efforts to be fluent in English such as the level of frequency you use to speak English, listening and watching English medias, and most importantly to practice conversation with a native speaker. The more you speak English and devoted your time to practice and learn English everyday, the sooner you'll get to speak English fluently. If you're really focused and commited on that, I'm 100% sure that you'll speak English fluent in a year and even less than a year. 

It depends on your practice but certainly if you went abroad, your level can get better in a shorter time 

It depends on your definition of fluency, your motivation, your goals, your practice frequency. But, in general, practicing every single workday  and speaking every week with a native, in a year you could achieve a very decent level of English.