What is one to do with his laundered clothing before the nine days?
It is forbidden to wear freshly laundered clothing during the nine days [even if they were laundered prior to the nine days]. The following will thus discuss what one is to do with his freshly laundered clothing in order to be allowed to wear them during the nine days.
B. Pre-wearing before the nine days:
One is to wear his freshly laundered clothing [i.e. shirts; pants, bed sheets, bath towels] for some time prior to Rosh Chodesh. Doing so allows one to wear the clothing during the nine days, as its “freshly laundered” status has been removed.
For how long should it be worn for? It suffices to wear the clothing for even a mere moment.
May one wear more than one clothing at a time? One may wear more than one clothing at a time for this purpose. [Although care must be taken to put on one piece of clothing at a time or remove one piece of clothing at a time, due to Shichicha.]
Undergarments-socks, undershirts, etc: There is no need to wear underclothing before Rosh Chodesh, as such clothing may be worn during the nine days even if they are freshly laundered. One may thus wear fresh socks, undershirts and underwear as necessary. However, some are stringent in this matter.
C. Other alternatives-If one forgot to wear the clothing before the nine days:
Wearing on Shabbos: Alternatively, one can wait until Shabbos and wear the clothing for some time on Shabbos. However, this only applies if it is apparent that he is wearing these clothes as Shabbos clothing and is not merely preparing for the weekday.
Giving it to a Sephardi to wear: Until the week of Tishe Beav, one can give his freshly laundered clothing to Sephardi to wear in order to remove its freshly laundered status from it.
If one forgot and wore a freshly laundered garment without having worn it beforehand, must he remove it?
 Beis Yosef 551 in name of Ramban; Kaf Hachaim 551:56
 Michaber 551:3 regarding the week of Tisha B’av and Rama 551:3 and 4 that we are stringent beginning from Rosh Chodesh Av
Ruling of Michaber and Sephardim: The Michaber ibid rules it is only forbidden to wear freshly laundered clothing during the week Tisha B’av, and so is the Sephardi custom.
 So rule regarding Aveilus that another person can wear it: Rama Y.D. 389:1 and Shach Yoreh Deah 389:4; Kol Bo; Semak; Kitzur SHU”A 211:9; So rule likewise here regarding the nine days: Ben Ish Chaiy Devarim 6; Kaf Hachaim 551:91; Piskeiy Teshuvos 551:17
 Shach Yoreh Deah 389:4 regarding Aveilus that another person can wear it “Some amount of time and not specifically an hour and so is the custom”; Ikarei Hadaat 36 Samech; Misgeres Hashulchan 389 that so is custom; Daas Kedoshim 389:3 regarding Shabbos; Nitei Gavriel Vol. 2 10:1
Other opinions: Some Poskim rule one is to wear it for 2-3 hours. [Levush 389; Rav Poalim 4:29] Others rule one is to wear it for one hour. [Yosef Ometz p. 330; Ben Ish Chaiy Devarim 6; Kaf Hachaim 551:91; Piskeiy Teshuvos 551:17] See Nitei Gavriel ibid footnote 4
 Daas Kedoshim Y.D. 389
 Admur Kama 2:3; Basra 2:3; M”A 2:3; Arizal Shaar Hakavanos Inyan Birchas Hashachar
 Ateres Rosh Shaar Yom Hakippurim 2 [p. 29]; Shulchan Hatahor 2:1 [Komrono]; Minchas Aron 22:12; Yayin Tov 11; Shraga Hameir 4:87
 Divrei Nechemia Y.D. 27 p. 142 “Undergarments which receive sweat are not considered a garment”; Yifei Laleiv 400; Aruch Hashulchan 389:6 regarding after Shiva “People are not careful to give the undergarment to others to wear” and 389:7 regarding undershirt even during Shiva; See Lachmei Todah 30, brought in Pischeiy Teshuvah 389:2; Gesher Hachaim 21:10-1; Minchas Yitzchak 10:44; Pnei Baruch 18:10; Nitei Gavriel Vol. 2 10:3-4; In Vol. 1 111:8 permits socks in a time of need based on Poskim in footnote 10
 See Ben Ish Chaiy Devarim 6; Kaf Hachaim 551:91; Orchos Rabbeinu 2:132; Minchas Yitzchak ibid in his explanation of Lachmei Toda
 Lechem Hapanim 376; Kerem Shlomo Y.D. 389 in name of Lechem Hapanim; Minchas Yitzchak 10:44; Piskeiy Teshuvos 551:17; Nitei Gavriel Vol. 2 10:5 [However, see there that it must be placed on a dirt floor, and not a tiled clean floor.]
 See Piskeiy Teshuvos 551:17 footnote 103
 Ben Ish Chaiy ibid; Kaf Hachaim ibid; See Piskeiy Teshuvos ibid footnote 115
 So is understood from Rama Y.D. ibid
 Daas Kedoshim 389; Nitei Gavriel Vol. 2 10:1