This is the process I followed to establish a new starter. My current starter is fine but it seems to have mellowed over the decades and is no longer very sour. I recently started a new starter to see if the taste is any better.
Total preparation time is 7 days
I used wheat flour to get things started but slowly weaned it onto white flour once it became active because it will be fed exclusively on white flour and I'd prefer it got used to it.
I saw a strong rise on the second day but nothing on the third day. I believe this is caused by something else (bacteria?) in the mixture - not the yeast I'm looking for. I've seen this in the past and knew to just keep feeding it. Eventually you should get activity an hour or two after every feeding, with lots of small bubbles on the surface and the strong smell of alcohol after sitting overnight.
The yeast produces alcohol as a fermentation by-product and this will keep bacteria and mold from growing in your starter. Just be sure to scrape down the sides of your container after every use because I have seen mold develop on the dried flour clinging to the sides of an un-scraped container.