Don't drink a protein shake before cardio. After pro/fat meal depending on if it was a liquid or solid meal, wait 2 1/2 - 3 hours then hit the cardio, or do it on empty in the morning.
If you are ingesting carbs with your protein after cardio, wait 30-40 minutes to let lipolysis continue. If you are having a pro/fat meal, 10-15 minutes will suffice.