I've read a million different things about preparing powdered formula in advance and am still confused! Some things say you should only boil the water in advance, and then add the powder at the time of feeding. Others say it's okay to mix the powder and boiled water and store in a pitcher in the fridge for 24 hours.

For those of you who use powder formula, what's your process? I really want to figure out whatever the simplest thing is that isn't going to involve boiling water and mixing every couple hours.