It doesn't matter the time of day specifically, but it's whenever I've been awake for about 4 or 5 hours. Then I get all of the energy to do things for another 4 or 5 hours before I once again feel like a slug person.
I do like the early morning hours when it's like the whole world is asleep except for me, tho. When it coincides with my random-ass sleep schedule to where that time is in my 4-5 hour window of energy, it's the best time.