early in the morning and later at night when there feeding. What you most commonly hear though is the transition between light and dark which is about 20 minutes where the bass quickly transition eyesight and game fish take more time therefore making them almost essentially blind to the aggressive bass.

it depends on where you are, I usually catch them between June and mid August, and between about 6:30am and 7pm

In my opinion as long as its not too hot anytime is good. Even on days when it is real hot you can always fish the shade, deep water, etc. to catch bass. So you can never really go wrong.

Early in the morning, they are out feeding on the shad and other baitfish, and it is much cooler in the morning, and the bass will be a lot more aggressive too.