I think, there is no specific time period required by a person to become a professional trader. It may take several months to many years or it depends on a particular trader’s ability. The time required by a trader to become a professional trader it also depends on other factors. A trader must be discipline and spend good time in learning.
A regulated and rigorous practice is also needed so that a trader can develop some good trading skills. A Forex trader must be hard working and process good interest in learning Forex trading. In brief, if a Forex trader continuously work hard and spend good time in learning and practice then it may takes less time to be a good Forex trader or a professional trader.