I make up enough bottles with freshly boiled water & formula in the morning for that day. Then at night I makeup the next mornings formula and 2 bottles of water for the night, add formula to cooled water. This is cos I'm lazy and can't face going downstairs & heating up bottle during night. However after reading more I realise the formula isn't sterile so my night time practise isn't ideal. What do others do for night time bottles? Oh,& made up formula bottles are stored in fridge for 12-14 hours.