Setup, aka “shopping,” is a key component because you will have to wait for parts and fabrication orders to be completed and shipped. The lead time needed to get a PCB board is typically 18–30 days. That is, you wait up to a month from when you submit the order to have the boards in hand. Similarly, ordering electronic parts will have a shipping delay, plus perhaps additional delays if any parts are back ordered. This is why setup is broken out as a separate item.
It is best to get everything you need before you begin, so you are not wasting valuable build time waiting on supplies. Once you’ve placed your orders, you can then use the shipping window as a period to learn some necessary skills, such as picking up a ham license or learning SMT soldering techniques.