Well, unless it's the weekend, you can start right now. But seriously, among all financial markets in the world the forex market is unique in that it is open 24 hours a day 5 days a week except Christmas and New Year's Eve. (Compare that to he New York Stock Exchange working hours of 9:00 am to 04:30 pm.) We would have added an exception for national holidays, but whenever there is a holiday it usually affects only one country so traders in other countries could very well be trading. You should however take note and avoid trading on such holidays, especially on British banking holidays, as the market becomes thinner (less traders => less liquidity) and surprising nasty stuff can happen to the unwary.
Forex trading starts with the opening of the market in New Zealand, followed by Australia and Japan, who are later on joined by the European countries, and finally the US call it a day.
Always check the economic calendar for the day before you put in a trade. A calendar of the most import events is available right here.
|London (GMT)||New York (EST)|
|New York Open||13:00||08:00|
Note the opening time of the New York Stock Exchange (NYSE). Although currency is not traded on NYSE, there is oftentimes strong correlation between the moves of the Dow Jones Industrial Average index (DJIA) and the major currency pairs.
The UK trading session accounts for the greatest volume of forex market activity. That’s why about 60% to 70% of New York forex trading activity takes place in the morning hours while the best forex brokers in London are still open for business. However, oftentimes it is during the second half of North American trading that huge swings take place in the currency markets, especially on Fridays when the Yankees are left alone in a significantly thinner market.