| in my opinion the best time would be to do cardio either after weights or first thing in the morning.
This is better for two reasons..
1. Will minamise negative effect on strength exercises.
2. You prodomitly be using Body Fat for energy as you will either have no carbs in the body(am cardio) or you will have minamum carbs in the body for energy (Post workout cardio)
__________________  |