In what order should I set up territories, warehouses and store locations?

Work from the top down. Open Plugins, then Multi Warehouse & Store, which shows three steps: 1. Territories, the areas that group your warehouses. 2. Warehouses, created inside a territory. 3. Store Locations, shops or pickup points that take stock from a warehouse. Click Manage on each card to add them. The page also shows how many of each you have.