The best time to trade Forex is honestly whenever works best with your schedule. There is no particular set time that works for everyone, but virtually everyone can find some time or another that is going to work out great for them. As a result, it is important to think about this in your own context.
The primary factor relating to when you will select to trade Forex has to do with which time zone you are in. The Forex market largely revolves around what time it is in the United Kingdom. This is because this is a centrally located country upon which world times can be synchronized.
Finally, a factor to consider is when market news comes out on various currency pairs. The reality is that many pairs react the most when they are facing a pending news story. It is great for traders who can jump on this news and make the moves they need to make in order to profit the most in the market. With that in mind, consider planning trades around these times as well.