The best time to play poker is when the lesser skilled poker players are also playing.
This means I only play in the afternoon and evenings, with special emphasis on weekends.
However, from a personal standpoint, I tend to get tired in the late evenings and I lose all motivation to play when I get sleepy, I only want to head off to bed... so this means I generally won't enter tournaments that start later than 5pm... but that's just me. Some of the younger kids have infinite stamina and can play all day and night. I'm old now. LOL