Terrible Twos... 4 Months Early

Dr Hirsh warned me that Terrible Twos actually begin at 18 months. Let the record show that Aiden's began at 20 months. His tantrums don't last long but they are dramatic. When will he get sick of hitting his head on the floor from falling out backwards? He gets mad when I turn the cartoons off TV for a few hours or when he can't have GoldFish crackers for breakfast, lunch, and dinner.