While I'm not as versed in areas of cardio as some others here's my .20:
1) How long are you planning on doing cardio for? Add that to the time it takes to work out. That could be a while
2) I would think right after a work out you'd want to adress post training nutrition ASAP. Your body is in a depleted state after working out, and cardio COULD compound this.
3) I'm not sure that doing cario after a workout is better than doing cardio in the morning on an empty stomache. While a workout will depelete your glycogen stores, I'm note sure if your body will be as efficient at burning fat.
Lets see what everyone else says.