Will this harm my baby?

I have been making babies bottles with the tommy tippee prep machine but have just changed him to cow and gate comfort milk due to colic. This milk is thicker and harder to dissolve. At bedtime would it harm him to make a bottle with boiling kettle water at say 10pm for him to drink at 2 or 3am? By this time it will have cooled to room temperature? I know they advise to use within 2 hours but years ago this is how bottles were made and people still do it.