I used the powder, My daughter was on Nutramigen Hypoallergenic Formula was the only kind she could keep down. I did not make more then i needed. If she was taking 5 oz at the time i made 6. Putting 1 ounce in the fridge in another bottle. If she beeded it i had it, if she didnt , I would use it the next time i fed her.
To take togo, i would measure out the powder, put it in the bottle and put the cap on. I would take her nersery water and put in another bottle. I could heat it while i was out, Or under warn water in a sick if need be. Just put the water in and shake. Throw out any that is not used. That way baby always has safe formula when out too.
I had a small tupperwear container of powder that I carried in her baby bag. I made sure I used it up within the week and replaced it. Always had a spair bottle in the bag, and a never left hime without her water.