First off I completely agree with Scotty. Doing it when you can and will is the best thing.
I also have heard that aerobic activity in the AM helps your metabolism throughout your day while Anaerobic our strength training is good at night since your body uses sleep to recover.
There's no specific time to workout. All you need is an hour /day for two 30min hard sessions.
For me to kick start the day I would recommend workout in the morning for the extra boost of energy But as longe you workout and feel good about it every time is good