It's hard to imagine, not having ready to feed formula for baby. My mom would say proudly to other moms, "My baby was a 'Carnation baby" I guess a badge, because of the famous (I never heard of them) Pappas Quads. I also never realized what was all involved in sterilizing formula back then.
Preparing the Formula
One procedure is to sterilize all the equipment in one pot; boil the water for formula (10 minutes) in another pot; cool; measure and mix water, evaporated milk (already sterile) as it comes in the can. and any other ingredients your doctor orders, using sterile containers. Pour proper amount for one feeding into each bottle; cap; place in refrigerator.
An equally satisfactory and simpler method sterilizes equipment and formula all at the same time. After washing and rinsing all the utensils, mix the fresh milk or evaporated milk and water for the formula in any container and divide into a sufficient number of bottles to last one day. Cap bottles loosely (so that steam may escape) and stand them upright in sterilizer rack together with nipples (if they are not already included. Add cold water as directed for your sterilizer. If you use a pan bring the water level up to the level of the milk in the bottles. Cover, bring to a boil and hold at the boiling point for 20 minutes. Cool gradually to avoid the formulation of skin or scum which might clog nipples. Screw caps tightly; place in refrigerator to keep cold until needed.