Update Just checked the yoghurt after around 7 hours in the incubator and it's looking really good, quite set, but I'm going to leave for another few hours and then refrigerate. Will take a photo in the morning.I got an answer back from Cheeselinks and they said you don't have to be pedantic about the amount you put in, the lady herself never measures what she puts in, only adds a few grains and it works no problem, so that would explain how you are supposed to be able to get 250 litres from the packet. So it's looking good. The grains have been put in the freezer in a sterilized jar and the use-by-date is May 2012.