Wednesday, December 25, 2019 will be a federal holiday in the District of Columbia. This means the USPTO will be closed. This means that any action that would be due at the USPTO on December 25 will be timely if it is done by Thursday, December 26, 2019.
Also Tuesday, Dec. 24. See, for example, https://www.govexec.com/pay-benefits/2019/12/surprise-move-trump-gives-federal-employees-christmas-eve/161974/