This rye sourdough starter should take just five days to be ready, although it can be left longer if you wish. If nothing has happened by day six, it could be that your house is just too clean, or the air where you live is polluted and sadly lacking in natural yeast (very unusual, but it happens). You could stop using bleach or antiseptic sprays on your kitchen surfaces, and revert to hot, soapy water for cleaning, and try again. Sourdough needs germs!
Recipe taken from Perfecting Sourdough by Jane Mason, published by Apple Press (£14.99)