Buying a rug first before your furniture gives you a reference point to build from, which is why it is generally recommended if you are decorating a room. If you like the look of a darker-toned rug, for example, you could pair it with lighter shades around the room to create balanced and considered contrasts. However, rugs can also be bought later if you already have a foundational piece for the room - for example, a statement sofa or art piece. Generally, as long as you have already identified your colour palette and feel for the room, you can buy a rug at most points throughout the process.