Question:

Is it permitted to perform Eruv Chatzeiros before Erev Shabbos?

Answer:

Yes. It may be performed during any day of the week.

Explanation:

Although the classic sources which discuss the mitzvah of Eruv Chatzeiros all mentioned it being performed on erev Shabbos, nonetheless, in truth it is valid to perform it during any day of the week. So can be implied from the fact that no such invalidation is recorded in the sources regarding Eruv Chatzeiros, even though such an invalidation is recorded by some Poskim regarding Eruv Tavshilin which was performed before Erev Yom Tov. The reason for invalidation by Eruv Tavshillin, according to those who invalidate it when done prior to erev Yom Tov, is not applicable by Eruv Chatzeiros. Furthermore, the widespread custom is to perform Eruv Chatzeiros on erev Pesach which counts for every Shabbos of the entire year and hence even initially the widespread custom is not to do it specifically on erev Shabbos.

Sources: Admur 368:4; Siddur Admur; Rama 368:5; Rama Kol Bo 33; Shibulei Haleket 99; Kaf Hachaim 266:134; Kitzur SHU”A 94:11; See regarding Eruv Tavshilin: Admur 527:2; Michaber 527:14; Taz 527:13 and Rosh Beitza 2:1