Re: Kefir
I have similar situation. I got my little tiny kefir grain two weeks ago. I was amazed at how effective and how quick it makes kefir.
To answer your questions.
* The little grain I have is not enough to make a cup of kefir in 24 hours. So I leave about teaspoon of kefir from previous day in the same cup and add fresh milk. This way the kefir is ready for me in 24 hours.
==> How much you need to keep from previous day depends on how much you want to make for the next day and for how long. Experiment with it for a day or two then you will find out.
* The kefir is ready when you see sign of milk thickening. If you see thickened kefir and some kind of transparent liquid separating (the liquid is whey, I think), the kefir is over fermented.
* The kefir can be fermented anywhere in your house. Warmer place will ferment quicker. But cooler place will work jut fine.
* When kefir is ready but you don't want to drink it right away, move it in refrigerator to slow down the fermentation so it does not become too sour.