Are you allowed to wash the kitchen & bathroom floor on Thursday in honor of Shabbos during the 9 days?

If you do so every week, you may do it during the nine days as well.

Source:

ראה שו”ת התעוררות תשובה ח”ג סי’ ל’, מועדים וזמנים ח”ח ע’ פ”ה, ועוד.