I find it harder to motivate myself to work out in the evenings.
Its much easier to start off the day with a good workout.
In the evening you know your workout will take it out of you and then you'll have to go to work on top of it. And try to stay awake plus be physically drained as well.
I hope you find a schedule that works for you. I try to work out on monday, tuesday, thursday and friday. Sometimes that turns into skipping days, moving them to wednesdays and saturdays, or even working out at night...