Can a working person learn shenayim mikrah vechahad targum at night in order to finish lechatchilaa before Shabbos morning or otherwise time constraints?Theres Kabbalah not to learn mikra at night.
When there are time constraints, it is permitted to read shnayim mikra at night, in particular for those following Ashkenazi custom.
The Mishnah Berurah (Shaar Hatzion 238:1) mentions, citing from Be’er Heitev, that one should not read mikra (Torah verses) at night. This concept is derived from a teaching of the Midrash, which states that when Moshe ascended Sinai to receive the Torah, he studied the Written Law in the day, and the Oral Law at night.
However, the Mishnah Berurah cites an implication from the Peri Megadim whereby mikra can be studied at night, and concludes that although it is better to learn mikra in the day, there is no actual prohibition of doing so at night. Therefore, when there are time constraints, it is permitted to read mikra at night.
It is noteworthy that Sephardi authorities relate to the issue of studying mikra at night with greater severity (based on Kabbalah), the Ben Ish Chai explaining that night is a time of dinim (strict judgment), and is not suited to the study of mikra. Shut Yabia Omer (Vol. 6, no. 30, sec. 5) thus writes that one should only do so under extenuating circumstances.
Yet, Orchos Rabbeinu (Vol. 1, p. 123) testifies that the Steipler used to sometime read the second mikra on Friday night, and Shut Siach Yitzchak (116) explains that there is no problem in doing so, because the dinim (judgment) are not awakened on Shabbos.
Authorities dispute whether Targum has the same status as mikra concerning its study at night (see Chida, Machzik Berachah 9; Shaarei Teshuvah 1; Siach Ha-Torah Orach Chaim 238). For those who fulfill the obligation of shnayim mikra by reading Rashi, there is certainly no problem of studying Rashi at night (Kaf Hachaim 23).