So, once you have a desem, how do you take care of it?
For the second week (that is the week after it's been born, then grown in the in the incubator flour bed), it has to be fed every day. The thing to keep in mind is that you shouldn't feed it more flour than is already in it.
You start out with about 2/3rds cup of desem, which has 1 cup of flour in it. If you intend to bake at the end of the week, you will need to end up with 3 cups of flour worth of desem plus 1 cup to carry on as the "mother". So, you will need to feed 3 cups of flour to the desem during the week. That means 1/3 cup per day, plus 1 cup on the last day, or however you would like to divide it up.
The procedure for feeding the desem is: add half the amount of water of the flour you're adding (e.g. if you're adding 1/3rd cup of flour, add 1/6th cup of water) to the desem, soften it up, then add the flour, knead well, and return to the storage container in the cool location. Be careful not to get any salt into the mother desem.
You can always add more, as long as it's less than the amount of flour in the existing desem. Let's say you wanted to bake a small 2-cup loaf every day to see the progress. Then you'd add 1/2 cup of flour every day, divide the desem in half, and use that half + 1/2 cup of water + a teaspoon of salt + 1 cup of flour for the loaf. You can also create more desem than you'll need for the next baking, to create desem dosas  for example.
I'll be feeding the desem 1/2 cup of flour per day, but most likely I'll be waiting to bake the next loaf until next Saturday (especially since this week is going to be pretty busy.)