Day 6-10 of Starter:
Look for bubbles and for the starter to double in size and then fall. This indicates your starter is active and alive. Scoop out a spoonful of the starter off of the top and throw in the trash. Into the jar add 40 grams all purpose flour. Then tear (zero out the scale) and add 5 grams of Rye flour. Heat up filtered water to just boiling. Into a cup, add about 1/2 cup of the warmed water. Then add cool filtered water to it. You’re going for about 85 to 95 degrees F. Zero out the scale with the jar on it and add 40-45 grams of the warm water (using less water helps to thicken the starter). Stir the ingredients with a wooden spoon. The mixture should be thick and difficult to stir. Add a tiny bit of water, only a gram or two at a time, if the mixture is still dry. It should be wet, but on the thick side. Wrap the jar in a kitchen towel and place it in a warm spot, heated oven turned off, or a proofing box, overnight.
At this point, your starter is ready to use if it is doubling in size. You can also start to save the discard (the starter you scoop off of the top) in other recipes now. Keep it in a container in your fridge for up to a few days.
When you want to make bread, simply scoop off the top of your starter as usual, then add an increased amount of flour and water in the morning (70 grams all purpose + 10 grams Rye + 70-80 grams warm water) and allow it to double in size. It’s ready to use to make sourdough bread at this point.
You can also keep the starter in the fridge and feed it every few days at this point.
