Well, I have always heard that it's more effective if you exercise in the morning..before eating.
However, I know myself. And for as long as I can remember, I've found that if I try to exercise in the morning...I won't exercise regularly. But if I exercise at night, I get it done on a regular basis.
So...I'm going with what works!
If you are able to exercise in the morning, then you should!!! From what I understand, it's 3 x's more effective than exercising later in the day.