Sourdough

I have started a sourdough. In preparation for a class starting next week, I am experimenting with sourdough. It was started with potato water, flour, and a bit of brown sugar. I'm using a plastic container, with plenty of room for it to grow. In the past, I've had too much starter in too small containers, and it made a mess! The starter will bubble and grow in size, so I grabbed a large container.
It started to smell bad and get a layer of starter "liquor" at the top. I stirred it back in. The next day, I fed it equal parts flour and water.
A word about the flour: I am using Wheat Montana, Prairie Gold. Google it.
The starter kept bubbling, growing, and I fed it again. It continues to look and feel more like a very wet bread dough - elastic, nice color, strong smell. I fed it again in another 12 hours. I was sure to also scrape down the sides of the container, stirred it between feedings, maybe once.
Today, I am making biscuits. I have taken out one cup of starter, put it into a large bowl. I put the lid over (loosely) the starter and left it on the counter. After this next feeding, I'll put it in the fridge for use later in the week.
Then, I added a couple of cups of milk and white flour and about 1/4 cup of oil.
That's where it's at. Many recipes call for that mixture to sit overnight. Well, I'm going to probably get my shorts in a bunch and stir it up later. I started the biscuits about an hour ago. The starter is quite elastic, bubbly, and growing. We'll see how it goes...