My math shows that you’d need a 140% gain per year to get that goal. While I do think that’s [I]possible[/I], it’s probably not going to happen.
I’ve made that much in a year before, but I won’t make anywhere near that this year. And I can’t imagine doing it 3 years in a row. 
How much time per week do you have to devote to learning forex during those 6 months? If you only have a few hours per week after work then there is no way you’re going to be ready in 6 months. But, on the other hand, if learning forex is now your full-time job then it probably shouldn’t even take you 6 months.