Our prep machine isn't working right, DS has 6oz bottles and for some reason it keeps making 4/5oz. I'm not willing to replace it anyway so I'm going to make them up without it I just need some advice. The past few bottles I have used boiled water to make up the bottle and cooled it down in a jug of cold. I haven't waited 30 mins though before pouring it out the kettle, is this ok? It just doesn't work. What is the most common method? I'm thinking about trying the method of pouring 2oz boiling water in, add formula, stir then add 4oz of cool boiled water (using an old bottle to make sure the measurements are right). I don't have a jug with a lid though. Is there a certain type of jug I need to use? Is there anything else I need to be aware of?