Trading time is very important. Though the market remains open for 24 hours, all the time it doesn't behave the same. Sometimes it remains calm and sometimes it becomes volatile like in New York session. Your strategy will tell you which time best for you. For me I trade mostly in New York session.
When you trade is definitely very important, besides the different sessions it is worth knowing when news are released, when fixings are, etc. Also you should pay attention on Fridays not to forget about positions you don't want to hold over the weekend.
The movement of the Forex market is not always the same. And trading is not possible without flexibility in a changing market. The price should be flexible with the market as it is sometimes volatile and sometimes impulsive. I usually think the new work session is the perfect time to trade.
It is important for a trader to choose the moment of entering the market. You also need to understand where he will exit the deal. And in this case, one cannot simply be guided by time, one must look at the behavior of the market and prices.