I am going to rock your world, because the concept of clothes being prestigious through being fashionably made rather than just being made of expensive material is generally dated to the mid-14th century.

Around the 1350s, clothes that fitted the body were suddenly the focus of attention (attributed by many to the need to wear fitted, padded garments under plate armor). Instead of using rectangles and triangles taken from the full width of the fabric, tailors would cut smaller and curved shapes that resulted in wasted scrap fabric - conspicuous consumption! The same principle was behind the fashionable embellishment called dagging, cutting slashes, scallops, tabs, etc. into the edges of a garment.

When showing status only occurs through the cost of your fabric, there's no trickle-down effect. Everyone is constrained by their purse: the wealthy can afford to buy silk damasks, the middle classes buy decent but less pricey wools, and the poor make do with the worst. (I should mention that this was supposed to be restricted by birth as well, and most areas had sumptuary laws attempting to keep wealthy merchants from dressing like the nobility.) Cut, though, can be imitated. Fitted clothing was first worn by the upper classes and was gradually adopted by the rest. There was a need to change the cut over time in order to preserve the class distinction, which led to a continuous series of changes in fashion - slow at first, but gradually increasing over the course of the next century or so.