One should preferably light Chanukah candles precisely at nightfall (approximately twelve minutes after sunset this time of year), as we have explained yesterday. Some Ashkenazi Jews customarily light at sunset.
The Earliest Possible Time to Light Chanukah Candles
Chanukah candles should not be lit before this time (with the exclusion of Friday afternoon when the candles must be lit before sunset, as will be explained in one of the following Halachot). Even one who is busy and cannot light at the appropriate time may not light before this time, for many of the Rishonim are of the opinion that one does not fulfill one’s obligation before this time, even if one has no other alternative. However, if one is about to set out on a journey and is worried that he will lose out on the Mitzvah of lighting the candles entirely, one may, in fact, light before sunset beginning from the time of Pelag Ha’Mincha (which is one-and-a-quarter seasonal hours before nightfall). Nevertheless, one may not recite the blessings before lighting, as the rule is “when in doubt regarding the blessing, do not bless.” In any case, it is preferable to appoint a messenger to light on one’s behalf, and one will thus fulfill his obligation of lighting Chanukah candles in this way.
Nightfall
According to Maran Rabbeinu Ovadia Yosef zt”l, nightfall in Jerusalem is at approximately 4:53 PM.
In all other places, this time can be calculated by counting thirteen-and-a-half halachic (seasonal) minutes after sunset. The formula to calculate thirteen-and-a-half halachic minutes is to divide the day from sunrise to sunset into twelve equal parts. Every part is a halachic (seasonal) hour and each of these hours consists of sixty halachic minutes. This is what causes these thirteen-and-a-half minutes to be approximately ten regular minutes in the winter and in the summer these thirteen-and-a-half minutes can actually be longer based on the length of the day.
In New York City, sunset on the first night of Chanukah is at approximately 4:28 PM and the thirteen-and-a-half halachic minutes are approximately twelve regular minutes during this time of year. Hence, the proper time for lighting Chanukah candles in New York is at approximately 4:40 PM. (There are precise calendars on the market today which correctly portray halachic times according to our traditions, such as the “Ohr Ha’Chaim” calendar in Israel and the “Zemaneh Yosef” for locations all around the world. The “Zemaneh Yosef” calendar is available on Apple and Android App Stores. Only these calendars should be used as no other ones accurately reflect the opinions of Maran zt”l.)
Yoshev Be’Seter
There are those who customarily recite “Yoshev Be'Seter” (Psalm 91) seven times after lighting the Chanukah candles. Sefer Tashbetz (Ch. 258) writes that the Hashmonai family recited this Psalm seven times and then the final verse “Orech Yamim Asbi’ehu” twice before going out to wage war against the Assyrian Greeks, and they were eventually victorious. Some quote this Segulah in the name of the Ramban and being auspicious for protection all year long.
This Segulah is also quoted by Rabbeinu Chaim Palagi in his Mo’ed Le’Kol Hai and Rabbeinu Yosef Haim in his Ben Ish Hai. Nevertheless, not everyone observes this custom, and it is certainly not obligatory. (After lighting Chanukah candles, Maran zt”l would immediately return to his Torah study or discuss Chanukah topics with his family, but would not recite this Psalm.) Hagaon Harav Shalom Cohen zt”l, late Rosh Yeshiva of Porat Yosef, said that one need only recite the verse “Vihi No’am” seven times followed by “Yoshev Be’Seter” only once.
******
Clarification: we have written that one who lights Chanukah candles at Pelag Ha’Mincha due to extenuating circumstances should not recite a blessing due to a disagreement among the Poskim. However, Maran zt”l rules (in his Yechave Da’at Vol. 7, Ch. 103) that one should, in fact, recite a blessing in this case, based on the ruling of the Peri Chadash.
