it depends on what your are trading and what sort of traders you are. this is what I do for day trading futures : Asian session : 30 minutes premarket and 2 hours after opening And on Friday, 2 hours after Asian lunch time. European session : 3 hours after opening and at times 1 hour premarket. At times I trade the whole European session (about 8 hours). US session : 2 hours after opening Choosing the right timing is very important as I don't want to miss the signal. But we can't possibily trade for very long due to our human body / mind limitation. -------------------
If opening gap, you need to guess which of the "gap plays" it is if you want to make some money on it... Might be worth your while to read up on gap plays.
Often I could not find a counter party to take my option position unless I traded the first few minutes after market opened, when volatility and uncertainties were high. I think market makers were more willing to deal at market open, perhaps because they had more flexibility to hedge their positions and they knew more than I about market direction? So, when I desperately want to close out (or roll) a position I usually do it right after market opens.