A few months ago we started "training" with solid food as well. For some time none of the kids ate very much and they still drank as much formula as they used to. But suddenly this changed. Over the last two months or so first Elin refused the milk bottle during the days, and then all three started accepting food in much larger quantities. We now serve them breakfast oatmeal, fruit purée snack, some lunch, another fruit purée snack, dinner and more oatmeal every day. They get milk (formula) during the night and at bedtime.
And the formula consumption has drastically changed. A box that used to last one day now last three or four days. We used to mix formula a liter at the time and keep in the fridge - now this is waste of space!
So we are approaching a milestone; the day we can say "No milk today!". We'll have a bottle of sparkling wine ready for the day we finally get rid of the milk bottles. :)