I think that this thread should be linked with eating too. Because eating throughout the day then going to the gym will pay off more. So for me personaly the best results will come around 6 pm, because I have ate through the day, my body if ready and well adjusted, for me its the perfect time. Then I will go bed about 11 at night, so maybe theres no 'correct time' but surely eaten will link to when you work out!!