A Designer Weekend, sometimes known by its American name, a 'Trunk Show', is an event where a boutique will preview a selection of the latest gowns from a designer. This will usually take place over a weekend, hence the name, Designer Weekend.
It's a great idea to shop for your wedding gown at one of these special events as the collection will preview a variety of styles that the boutique doesn't usually stock. Boutiques tend to know what sells well locally and will pick similar gowns at similar price points to stock in-store, therefore at a trunk show you might pick up something more unique or something you wouldn't have usually got to see. With the focus on one designer you will be able to get to know their quality and style in-depth, pick up catalogues, view their matching accessories and maybe even benefit from a discount.