Strength, flexibility, and endurance fare better during the hours of 2pm-6pm when your body temperature is at its highest. Reaction times are also quicker during this window making it ideal for HIIT workouts. Afternoon or evening workouts may also help you to stay motivated, especially if you're not a morning person.

It does not really matter. If anything, studies have shown that the best results (based on time of day) is the one in which you feel most comfortable. The happier you feel in the gym (rather than slogging through, tired or hungry or full from a meal or something) the better your results will likely be.