It takes a long time to order a bridal gown, so you should always start shopping nine months to a year in advance.Find out about how long it takes to order a bridal gown with help from a bridal fashion professional in this free video clip. Part of the Video Series: Wedding Dresses & Fashion.e specialize in sizes 12 and up. Today, we’re going to talk about how long it takes to order a bridal gown. Ladies, when you go wedding dress shopping, you have two options. The first is, you can buy your gown off the rack or right out of stock.