I have one every morning with breakfast, one on morning break about 11am one with lunch about 2pm, one after the gym or boxing (so every night weeknight about 7PM after gym and 9pm after boxing) and then one before bed about 11PM usually with a bowl of Bran Flakes. I also mix 100 grams of instant oats in with every shake for LOW GI Carbohydrate which I finds really helps.

As Jon also said, eat clean foods before bed as well as this is when your body is rebuilding itself after the gym. You wouldn't starve yourself for 8 hours during the day, so why would you at night

Also treat them as a meal supplement, NOT replacement and then 5grams of creatine everyday will also make a massive difference. In a pint of water with breakfast on non training days and straight after your workout or in your water bottle on training days.