In ancient times, wealthy families generally began preparing their daughters' dowries from the moment they were born. This included furniture, bedding, jewelry, clothing, and so on. Naturally, this also encompassed the bride's wedding dress and veil, which had to be hand-embroidered by themselves. Some wedding dresses could take years to complete.
I remember watching a TV program in my past life that introduced the ancient Thousand Skills Bed, which also took years to make.
However, in the countryside, poor families didn't have such troubles. They only started preparing the dowry after the betrothal. The rich gave more, while those without money sometimes had no dowry at all. Regardless, the wedding dress still had to be personally prepared by the bride's side, and even the simplest ones took months to embroider. For example, Liang Xiaoyu began working on her wedding dress after she got engaged to Yang Xiaoliu, and now it was only half done.