If you are doing scalping you can consider 5 mins - 10 mins time frame and if you are doing day trade then you should consider 4 hour - 1 day time frame to be more accurate therefore Well there is not a fixed best time since a good signal can appear in any time as The best time to open trades are when either European or united states market is open so that you can have volatility from the two markets and be able to trade with ease but well such a question cannot be answered by any of us in fact Just follow one or two major currency pairs, its also good because our attention will remain on only one or two pairs and we can take the right decision on right time if we focus on many pairs than our decisions will be late.