You shouldn't have to decrease his milk or bottles now because he still needs every feeding you give him.
Can you tell me when you put him for his nap? And does he seem hungry after you feed him his cereal, or his afternoon veggies? If so, you can gradually increase the amount of these, or you can add fruit or veggie with the cereal. See if he still takes a good BF too, and then you know you're on the right track.
Right now our schedule looks like this: Feeding is usually consistent, sometimes naps aren't.
7:30am Wake & 6-8 oz Bottle
9:00 am Breakfast Cereal & veggie
10am Nap
12pm Wake & Usually 6oz Bottle
1:30pm Lunch Yogurt & Fruit
2:30 or 3pm Nap
4:30 Wake & Usually 6oz Bottle
5:30 Dinner Cereal & Veggie or sometimes hard cooked egg yolk & Veggie
7:30 6-8oz bottle & bed
Sometimes she's not starving for her bedtime bottle, so I don't give her as much solids at dinner time.