Q. The Gemara in Pesachim 112 says not to wear clothing for eight days after they were laundered. But there is a takana of Ezra Hasofer to launder on Thursday to have clean clothing for Shabbos (a day later). How are we to reconcile this?
A. Indeed Talmud Pesachim 112b mentions in the name of Abaye that "one who washes his clothes and does not wait eight days before donning them again causes lice to rejuvenate and can cause tzoraas."
However, Ben Yehoyada maintains, as is obvious from the Gemara, that the above only applies to clothing that was infected with lice, but garments that was not infected or had the lice shaken off before washing, can be worn immediately after laundering. He adds that this is the reason we do not wait eight days in our times. However, Taama DeKra (1) mentions that the Chazon Ish was careful in this regard, and did wait.
The simple answer is is that one washes clothing on Thursday following the Takana of Ezra (Baba Kama 82a), but it is for honoring the next week's Shabbos. and one uses it the week after.
Horav Aharon Miller Shlit'a added that there is an opinion that the eight days are counted from the day the clothing was last used.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a