I don't follow the official guidelines but HV said I was doing it as safely as possible without following their advice.
I make enough bottles up to last 24 hours and store them in the fridge.
I use the little pots designed for taking formula powder out and about, and measure the powder for each bottle into the individual pots. It stops the scoop getting steamy and clogged up when tipping powder in over hot water numerous times.
Boil kettle.
Bottles already scrubbed and sterilised ready to use.
Pour boiling water into bottles, then tip the formula into each bottle from the individual pots straight away. Formula going into boiling water kills bacteria that might be lingering in the powder.
Put teats on, then unscrew and re screw teats to release any trapped steam.
Lids on, shake thoroughly.
Leave out on kitchen counter until completely cooled to room temp. Usually about an hour.
Store in the fridge.
If going out I take prepared bottles in a cool bag with an ice pack and flask of boiling water for warming them up.
I warm bottles up as required and use or dispose of them up within 24 hours.
I have two full sets of bottles so one is in use and there is always a clean set in the closed steriliser ready to use.
I do it this way as I find it quicker to warm up a pre made bottle up, rather than make each one from scratch then bring down to a suitable temperature. A screaming baby deciding they are hungry earlier than you expected isn't much fun!
It's not a case of being 'allowed' it's just advice on the current safest way to do things.
We live in a country where water is clean and we have access to adequate sterilising equipment, so I believe risks are minimal as long as good hygiene and sterilisation is practiced.
HCP and formula companies have to be strict on guidelines because some people can be slack with hygiene. Also some places it could prove very unsafe to use formula if they don't have access to adequate facilities to prepare it safely.