It is an institution of Ezra for one to do laundry on Thursday in honor of Shabbos, in order so he have clean white clothing to wear on Shabbos. This is in contrast to one doing laundry on Erev Shabbos, as on Erev Shabbos there is no time to do laundry due to the need for one to deal with the Shabbos preparations.
May one today do laundry on Erev Shabbos using a washing machine?
Although today it is possible to wash clothes with much less effort and time then was required back in the times of the Sages, nonetheless one is to still fulfill their decree to not push off the laundry to Friday. Nevertheless there is no prohibition to do laundry on Friday if one needs. Furthermore some Poskim rule that today with the use of washing machines there is no restriction at all in doing laundry on Friday rather than Thursday.
May one launder his Shabbos clothes prior to Thursday?
 So rules Mishneh Halachos, brought in back of Piskeiy Teshuvos Shabbos, and so rules Rav SZ”A [SSH”K 42 footnote 13] on the basis that today we are accustomed to wash clothing for many days worth. However earlier on in the footnote there a suggestions is given that the decree perhaps no longer applies today. It seems from Ketzos Hashulchan 73 footnote 22 that he too learns that the decree of the Sages is applicable at all times.
 SSH”K 44 footnote 13; Oar Letziyon 2/16; Yechaveh Daas 7/18; See Piskeiy Teshuvos [new edition] 242/10
 Rav SZ”A in SSH”K 42 footnote 13.