Question:

Am I allowed to cut nails on the day before Erev Yom Tov or does this at the same status as Thursday on which we don’t cut nails because it will grow back on the third day which is Shabbos, and hence so too regarding Yom Tov we should avoid cutting nails on the day before Erev Yom Tov being that it will grow back on Yom Tov?

Answer:

One may cut his nails on the day before Erev Yom Tov, although [even aside from the above reason] it is best to initially cut them on Erev Yom Tov itself.

Explanation:

We do not find any source or mention in the original custom of avoiding cutting nails on Thursday to extend this to also avoid cutting nails on the day before Erev Yom Tov. Now, although seemingly the reasons are the same, and just as we should try to avoid having the nails start growing back on Shabbos so too we should try to avoid having them start going back on Yom Tov, nevertheless, this entire concept is a mere custom followed by some, and seemingly a custom was never adapted regarding Yom Tov. Perhaps the reason for this is because there is usually two days of Yom Tov [i.e. Rosh Hashanah in the whole world, and all other holidays throughout the entire diaspora] and it would be belittling to the second day of Yom Tov to avoid cutting the nails the day before Erev Yom Tov, but cut them on Erev Yom Tov, even though it will start growing back on the second day of Yom Tov. Now, since the entire concept of avoiding to cut the nails on Thursday is a mere custom, and is done in order not to belittle the day of Shabbos, it would be inappropriate to adapt this custom regarding Yom Tov, which would automatically lead to a belittlement of the second day of Yom Tov. Whatever the case, the Mateh Efraim explicitly rules that if one needs to do so, then one may cut the nails on the day before Erev Yom Tov.

Sources: See Mateh Efraim 625:13; Shevet Hakehasi 1:105; Piskeiy Teshuvos 260 footnote 51 [writes to forbid]  See regarding cutting nails on Thursday: Admur 260:2; Taz 260:1; M”A 260;  Rashal in his glosses on the Tur; Mateh Moshe 411 in name of Sefer Hagan; Machatziz Hashekel 260:1; M”B 260:6 in name of Elya Raba