We were wasting so much formula because the package says to throw out any unused formula after LO starts eating. I asked our Ped about this and she said that we can put it in the fridge after LO stops eating and use it again for the next time. She said we can only do this once. Just wanted to share in case others were wasting a lot of formula as its not cheap.
I don't know if it makes a diff, but I serve LO room temp formula (mix with bottled water that is sitting on counter). I then put left over in fridge and warm it up (so I am only warming up the formula once if there is any left over).