How to prep formula?

I premake the formula with the boiled water and cool it straightaway. Then I keep it in a flask for max 24hrs in the fridge. Once my baby wants milk I just heat it up in a milk warmer. Makes the process especially during the night a lot easier and faster.

It is the only option I found for not having to constantly boil water and letting it cool down under the tap..

We use the kettle then nuby rapid cool, makes it right temperature in under 2 mins
When we go out we use a thermos flask we got from John lewis was only 20 pounds and keeps the water above 70 degrees for over 6 hours, then a rapid cool xx