Christmas decorations are traditionally put up in the days leading up to Christmas Day, on December 24th or 25th. However, the exact timing can vary depending on personal preference and cultural traditions. Some families may choose to put up their decorations earlier, such as the first week of December, while others may wait until after Thanksgiving or even after the first snowfall. Ultimately, it's up to you and your family to decide when it feels most appropriate to put up the decorations, and when they will bring the most joy and excitement to your home.