Nutramigen advice

Hi, new here, my baby has just started Nutramigen 1, it says to make fresh each bottle when needed (which just isn't possible as I never know when baby is gona go from 0-100 crying for a feed)...my question is, it also says it should only stay at room temp for 2 hours (normal formula you can have out for 6 hours)...does anyone know if I leave it out for longer (for his night feed, I could have it by my bed) does it make the milk bad? 

Long question there....Thanx for reading x