It makes sense to me that doing cardio on an empty stomach is best for fat loss, which would be your main reason for doing it, right??? your glycogen levels are depleted, for this reason the fat burning process will be jump started quicker. I believe that if you eat carbs prior to cardio, the calories from the carbs will be burned off first. This isnt optimal.
Also, why would you have a pwo if you dont weight lift that day. The purpose of the pwo is to restore muscle glycogen that had been used up during weight training. If you dont weight train, you dont need the pwo. NO BENEFIT WHATSOEVER. Actually, the extra sugars will definitely hurt your diet. This is a fact, not just my opinion, so take it for what its worth.
After cardio, wait 30 min, eat a fat/pro meal. By the time of your next meal, 2-3 hours later, you would be ready for pro/carb meal. By doing this you are prolonging the fat burning process. FYI, eating carbs after cardio, halts the fat burning process!!!!