My most creative time of day is early morning. I like get up, make a cup of coffee and get straight down to painting. Still being half asleep seems to make the work and ideas flow much easier than later in the day.
My most creative time of day is late at night after the kids have been tucked into bed. The house is still and quiet and I know there will be no interruptions. The phone will not ring, no one at the door, even the pets are sleeping peacefully. I can submerge myself wholly in my work and time just goes by without my notice, this is when my best work is created.
My most creative time of the day is usually when the muse strikes me and I never know when that is going to happen. I will say, though, that many of those times seem to happen when the day is almost over and everything is quiet. Nothing pulls me away from creating and that is nice!