I suggest:
Dear Honorable Speaker Nancy Pelosi:
The impeachment trial of President Donald J. Trump that the House has requested will start Tuesday, January 7, 2020, 9am. Please be fully prepared to present and prosecute the case of the House of Representatives at that time.
Merry Christmas and Happy New Year,
Mitch
All Mitch has to do is to set a date.
The TV cameras will be rolling at that time.
The Democrats have to show up and play ball.