I don't know what time management will do in the forex market. Even if it does something , I believe this is not a serious point of consideration and anyone who is interested to trade forex must understand that time management may somehow be nnecessary , but the real factor for which prediction of upward and downward movement of forex market is the most important and that is what you will use to trade profitably in the forex market without having to lose much of your money as a lot of people are doing.
I could understand the fact that Forex market may be so volatile that you will need to schedule your time and know when to trade and when not to, but this will solely depend on who is trading. The most important thing here is your understanding of technical and fundamental analysis because it is one of the needed skill that you must have to be able to trade forex market perfectly.
A lot of people might decide to trade in the morning while others might also arrange their time to trade in the afternoon, all of this will boil down to your understanding of forex market as a whole