When glycogen stores are full, the liver then converts it to fat, usually stored in the abdominal cavity if doesn’t have enough time to distribute it elsewhere (usually when you consume too many simple carbs eg sugar). It takes about 6 hours for your body to burn the glycogen stores before reverting to burning fat during rest and recovery (sleep), during fasting time of sleep. This being the case, the earlier you stop eating in the evening (preferably no later than 9:00pm) the earlier your body is going to tap into the fat stores. And depending on what time you are going to wake up in the morning will depend on how many hours of constructive fat burning you have.
For example, if you eat your last item at 9:00pm then your body will start burning fat around 3:00am (approx). So if you are not going to wake until 7:00am, then you have an awesome 4 hours of fat burning. This is however also dependent on you having quality sleep so that your cortisol hormone is low. If you wake or have a restless sleep, then this is going to effect your fat burning. If you do not eat enough quality food (protein, fat, fiber, and complex carbs) your body will not be able to repair and recover efficiently and so will also effect your fat burning.
So don’t eat too late at night, get plenty of quality sleep and eat nutritious food, and you will burn a stack load of fat when you sleep!!!