To set a Rye Starter down, start a week before you need the bread. Once up and running your starter will improve with age, as we all do, and will always be there ready to use. If you look after it and want to bake bread every day then it will need feeding with enough flour and water each day at least 12 hours before you need to start making bread.
If you bake once a week then feed it as soon as you have produced your last loaf, cover and put it into the fridge. Unfed it will last a month, but should be removed and fed at least 12 hours before re-use, using warm water to get it going again.
A nice thick creamy consistency just thicker than a Yorkshire pudding batter should keep a nice balance between flavour and baking performance – for those of a scientific bias, the pH should be between 3.5 and 4.
Making your Rye Starter
Place 50g of medium rye into a medium sized mixing bowl and add 75g of warmwater. Beat to a creamy batter, cover with a plastic bag to keep the moisture in and stand in a warm part of the kitchen but not directly onto a radiator or above the cooker. It will be happiest at 18 to 22°C if possible and leave it for 24 hours without disturbance.
Next day add another 25g of rye flour and 35 to 40g of warm water, mix and set aside as before.
Repeat this process for the next five days. By then your starter will be active and you will feel the gas bubbles between your fingers.
On the 6th day you will have about 500g of starter in the bowl and it is now that you need to decide what breads to make and how often. It may be advisable to split the starter in two and freeze one half as a backup. The yeasts will recover even after freezing - give it one good feed of 75g of flour plus 100g of hot water, stand at room temperature for at least 12 hours then it will be ready to bake with or restart your main starter.
As ever, there are as many many different interpretations of a rye sour as there are ideas on producing and keeping a starter. Keep it simple. Once you understand the basics then experiment with some of the more complicated formula's you will read in the recipe books.