We have introduced a new widget named Holiday Settings in the General Shipping Settings page. The widget gives you an overview of upcoming holidays and allows you to customize the holidays to better match with your operational schedule and fulfillment capability. You will now have the opportunity to override a holiday and present faster customer promises for your self-fulfilled offers.
There is a set of public holidays predefined in Seller Central. When estimating shipping date and delivery date, holidays are not counted as operating days. Therefore, estimated shipping date and delivery date that fall on holidays would be pushed to the next operating day. If, however, you have the operational capability and want to keep handling and fulfilling customer orders on a predefined holiday, you can now customize the holidays by overriding them to operating days. Find more details in the Help page. You can click here to customize your holidays.