My only suggestion is to go with what motivates you more. If you're too tired at night your energy and enthusiasm may lack, if that is the case than maybe do morning. Everyone is different, I'm a morning workout person and feel I get the most out of my workouts in the morning and it sure starts my day off with a positive attitude as well as gives me energy throughout the day........ Oddly enough my wife is the exact opposite, she likes evening workouts so it depends mostly on when you're most motivated. Just my opinion, hope it helps :) keep up the good work!