Your starter will begin smelling very fragrant after day 5. Before day 5 it might smell very sour and musty. Don't fret yet. As long as there's no mold and you're keeping up with feeding it properly, you'll be fine. After it has successfully fermented, it will have a very lovely yeast smell to it, almost vinegary, and it will be full of bubbles. It can take up to 7 days of feeding your starter before it is ready to use. It will become very bubbly and active. Once it is ready to use, you’ll take out what you need and add flour and water back into the mixture every single day. If you are not going to make bread every week, then you can refrigerate the mixture and feed it once a week. However, it does much better just staying on the counter and feeding it daily.