'Ezra HaSopher (the Scribe) instituted that we should wash our clothes on Thursday in honor on Shabbath. Since Fridays are very busy with preparations for Shabbath, one's main laundry should not be done then. Those who generally do their laundry for Shabbath during the day on Friday, should start doing it on Thursday instead.
Even someone who has a lot of home help and doesn't need to do much preparation himself or herself for Shabbath, should, nevertheless, have the laundry done on Thursday because the Rabbis didn't differentiate between the different cases and this ordinance of Ezra HaSopher applies equally to all people. Based on this, it would seem that the fact that we have electric washers and dryers nowadays, doesn't change the fact that the washes should be done on Thursday.
Having said this, small items such as handkerchiefs and the like, may be washed during the day on Friday, although it is better to wash them on Thursday also. In all cases, little children's clothes which get constantly dirtied, may be washed during the day on Friday.
(See Meqabsiel, 2nd year, Lekh Lekha, Oth 15)
Mekavtziel, Meqabsiel, shabbath, laundry for shabbat, shabbos, Laws of Shabbat