I would follow the nuby instructions if using one as we read you boil water, to sterilise, pour correct amount into nuby straight away, it will instantly start cooling, add the desired scoop to nuby, as water will be correct temp to kill bacteria but not destroy nutrients, shake and wait for green light Unless I’ve misinterpreted it
I was told by my health visitor that it’s within 30 mins. So when the kettle has boiled you can use the water straight away or up to 30 minutes but no longer as the water is then not hot enough to kill bacteria. I wouldn’t use the rapid cool for the water to make up bottles unless you use the hot shot method (putting the formula with an oz of boiling water, then cooling the rest of the water and topping up) x
Measure out 3oz of water (ex) pour most into the nuby leaving just under 1oz in bottle, this will kill all bacteria..turn nuby over. Put formula scoops into 1oz water. Swirl. Put the cooled nuby water in x