I think the best time to exercise is when you feel best exercising- if you're not a morning person, then scheduling exercise at say, 6.30am isn't going to help much at all because you won't be motivated. When you've got your roster for the week, perhaps you could sit down and plan out an exercise schedule? I work funny hours too, and have found that if I've scheduled it in, I make sure I go. Before I started doing that, I'd put off the exercise until it was too late to do anything (I go to bed pretty early
). Well done on joining the gym!