The poskim write (Shemiras Shabbos K’Hilchosah 42:15) that since we are accustomed to keep dinim of aveilus until midday on the 10th of Av, one is not allowed to wear freshly washed clothes before that. Although we mentioned, one is allowed to wash clothes before that, one should still refrain from wearing the freshly washed clothes until after midday. However, if one is travelling somewhere on erev Shabbos and he wants to wash himself and put on his Shabbos clothes before midday, he is allowed to, and he doesn’t need to wait until after midday to wear them, as in the end of the day he is putting them on in honor of Shabbos.
(A large amount of the above is based on a Teshuvah written by R’ Yom Tov Sanger, in Madanay Yom Tov)
