My wife is intent on sourdough bread herself. She's picking up 20lbs of organic flour tomorrow.
You can accelerate the process by adding grape or potato skins to the flour, or any local fruit. Once it starts bubbling you are good to go. Our starter is fed a 1/4 cup each dry milk powder and potato flakes and a cup of flour each time it’s used plus water at least once a month. Take out of the fridge, add the goodies, let wake up, use half to make bread and put half back in the fridge. Repeat indefinitely.In most parts of the country, commercial, retail packets of yeast have gone MIA.
Mix up non-chlorinated water and flour, 50:50. Let it sit out. Stir it once a day. When it rises, save about 10% of it to add to another flour/water mix. Repeat for several weeks. It depends on wild yeast. It seems to encourage the yeast better with whole wheat flour, rather than bleached. Micronutrients, I guess.
If you Google "making sourdough starter", there are a gazillion recipes.
If using rye flour for a starter you may be able to use it as soon as 4-5 days, as my understanding is that rye will ferment faster than regular flour. Let us know how it turns out!I had some Rye flour on hand and decided to try the starter mentioned on the BBC site (post 4). It seemed more than a little dry, so I added more water to make it like a batter. It may take a few weeks , but I'll let you know how it ends up.
I have two other starters. One is from Red Star brand and is labeled "Instant Sourdough". I started it eight months ago and it still works well, maybe a little bland. The second is "wild" that was started in the kitchen on just wheat flour and water, it's the more interesting of the two.