If you used only dextrose, you run the risk of a potential blood sugar spike and crash, leaving you with low energy.
Protein is an extremely important source of nutrition.
Aim to get this meal within 4-5 hours of completing the session.
 Including protein in your pre-workout can improve performance and increase protein synthesis.
Waiting until after your workout to have a shake may help with fuel replenishment and muscle recovery.
Chocolate milk is low in saturated fat and cholesterol.