Do I have to be careful to also cut my toenails on every Erev Shabbos, just as I cut my hand nails, and if so when do I have to cut them as I know we don’t cut both the hand and toenails on the same day?
Although it is a Mitzvah to cut one’s hand nails every Erev Shabbos, nevertheless, the Poskim conclude that there is no Mitzvah or obligation to cut the toenails on every Erev Shabbos in honor of Shabbos. Nevertheless, if the toenails appear long, then they are to be cut before Erev Shabbos, especially if one is accustomed to immersing in a Mikveh before Shabbos. Furthermore, the Arizal was particular to cut both his hand and toenails in honor of Shabbos, and so can be implied from Admur and other Poskim that also the toenails should be cut in honor of Shabbos. Practically, it is your choice to do so or not, however whatever you choose, you should not cut them the same day and hence the toenails should become cut Thursday and the hand nails on Friday.
Although it is a Mitzvah to cut one’s hand nails every Erev Shabbos, this is because the hand nails look repulsive when they are long. However, the toenails which are not visible are not considered a Mitzvah to be cut Erev Shabbos.
Sources: See in general regarding cutting the nails: Admur 260:1; Michaber 260:1; Kol Bo 35; Rabbeinu Yonah Hayirah 309; Sefer Chassidim 58; See regarding that this does not include the toenails: Ketzos Hashulchan 73 footnote 4; See regarding cutting even the toenails if one plans to go to Mikveh: Mateh Efraim 625:13 regarding Yom Tov that they should be cut two days before [so one not cut them and the hand nails on the same day], although perhaps this is due to Chatzitza before Mikveh, as it’s a Mitzvah for one to be Mitaher himself before the Regel, and hence would not apply to Erev Shabbos. However, seemingly the custom of the Arizal refers to even Erev Shabbos, and hence his statement in Alef Lamateh would imply that whenever one goes to Mikveh, such as Erev Shabbos, the toenails should always be cut. Vetzaruch Iyun. From Ketzos Hashulchan ibid it is implied that even if the toenails are long there is no need to cut them. See regarding the opinion of the Arizal: Kaf Hachaim 250:17; See regarding the opinion of Admur: Admur 260:1 does not limit the Mitzvah to hand nails and writes Stam “nails.” Likewise, Admur 260:2 and the M”A 260 and Maggid Meisharim Mishleiy 23:6, brings the custom to cut the nails only on Erev Shabbos and Erev Yom Tov and to not cut them on the same day, and therefore they write to cut the toenails on Thursday and hand nails on Friday, hence implying that the toenails are also included in the Mitzvah; See regarding cutting the toenails Thursday and hand nails Friday: 1st custom in Admur 260:2; M”A ibid; Maggid Meisharim ibid; M”B 260:6