I find my most creative time of day varies depending upon what I am doing.  For instance;
     I write most of my blogs between 9:00 and 11:00 in the morning.
     Most of my photo shoots with models are set for 3:00 to 6;00 in the afternoon.
     The Majority of my photo editing is done after 8:00 at night and can go on until very early the next morning. 
Photo editing is also determined by mood.
     Anger or frustration tends to make me create psychedelic work.
     Tension causes me to work using techniques that emphasize and isolate the subjects.
     When I am relaxed, I tend to pull up landscapes or my older shots.
     Sad times will find me going into my alien shots, as they tend to force smiles and change my mood.
Landscape shots or shots involving people in landscapes I prefer to shoot early morning or early evening.  Studio shooting is determined by either client's or model's schedule.  I actually will use my camera whenever I see something that piques my interest.  I tend to not edit my images until at least 24 hours after a shoot, so that any excitement that may cloud my judgment has had a chance to subside.  Editing is best done using fresh well rested eyes.
I plan a shoot about 24 to 48 hours before I have to take my camera out, unless models are involved.  Models are wild cards in that unless they are shooting a concept I asked them to shoot, I have to wait until they arrive and see what their ideas and choice of wardrobe will permit.  Shooting nudes is still a wild card in many ways as body type can be vastly different between similarly sized models based upon their fitness level and posture, but I do have a set concept for nude shoots that has usually been discussed at least 24 hours ahead of time.  When traveling, the only planning done is for the logistics of getting to and from a destination and the time of day simply determines the direction the camera is likely to be pointing.