I've done the following ... used a bottle warmer... which at 1st was ok but started to take to long once he got on bigger feeds, then i'd take a flask up with me, fill each bottle with so many oz of cooled water, add powder & fill with the flask to required oz amount & feed him, but now its just quicker to run downstairs grab one from fridge add powder & warm in microwave. 60 seconds of a job is much quicker than any of the others ive tried .