Don't be lazy, get up and do the morning cardio. lol. Yes you should do it in the morning on an empty stomach because you will burn the most body fat. By the afternoon, you have already eaten and your stomach will be looking for any fat to burn, not just body fat, so all fat eaten is fair game when it comes to using it as energy. Here's some other reasons to get up and do it earlier:
1) You will speed up your metabolism the rest of the day exercising in the morning.
2) You will have more energy th erest of the day.
3) You get it over with bright and early and have the rest of the day to looking forward to, no worrying about having to do it later.
4)Sometimes people blow exercising off completly when they are doing it late in the day because they are too tired, or have too many things to do and tell themselves they have no time to do it.