Depending on the shifts I work (I'm a nurse) and what I have on dictates when I exercise.
I prefer to do it in the morning. I find it gives me energy and also keeps me on track diet wise for the day. And if I have extra time at the end of the day I might fit in another walk, even if it's around the back yard with the dog. Moving = exercise. Doesn't need to be in the gym. If I have to do it in the afternoon I need to force myself at times to just put my runners on and do it. Rather than making up excuses that I'm tired or worked hard today. I always feel better after it.