thqat will depend on the market you intend to trade. The Europe open is 3 am ET, which is aheacy time for Eur trades. The other markets also have more active times
When London and New York overlap. I guess between 8 to 12pm EST. You'll find great volatility and liquidity. Unless you like getting up earlier. Say 1 or 2am EST to trade the european sessions? Opening breakouts from Asian session are a common theme.