Timing of Megillah reading
Shalom and thank you for turning to us. You say that you may have to choose one out of the two required Megillah readings on the evening of Purim and the day of Purim, and you want to know which one is preferable in a case when it is only possible to attend one reading.
The Talmud in Tractate Megillah 4:1 discusses this issue, where Rabbi Yehoshuah ben Levi states that one is obligated to read the Megillah on the evening of Purim (according to the Jewish calendar the day begins with the evening before, just as the Sabbath begins Friday night after sundown and ends Saturday night after dark, every festival begins on the evening before.) Purim this year is on Tuesday, so it begins on Monday night when the Megillah is read and the reading is repeated on the following day. This is brought down as Halacha, Jewish law, in the Shulchan Aruch Orech Chayim siman תרפז paragraph 1.
The accepted practice is to make every effort to attend both the evening reading and the reading by day. For men the reading by day should preferably be in a minyan during shacharit, the morning service, the blessings before and after should be heard and the listeners should answer Amen. A woman can fulfill her obligation by hearing a male over the age of thirteen read it from a kosher Megillah scroll, whether in the synagogue or elsewhere in a place where holy words can be spoken. (Words of Torah should be spoken only in a place where there is no overt immodesty, or a foul smell.) and if there is no one available to read it for her she can read it herself from a kosher Megillah scroll. If the man reading the Megillah for women has previously fulfilled his obligation to hear the Megillah, then he does not say the blessings, but rather one of the women says the blessings out loud and the others answer Amen.
In your case where there are apparently extenuating circumstances that do not allow you to attend both the evening reading and the day reading, you should attend the day reading.because the main mitzvah is during the day.
You are probably aware of the other mitzvot that need to be fulfilled on Purim. These include having a festive meal on the day of Purim. Halachically this means doing the ritual washing for bread and eating at least enough bread to say the Grace after Meals with the special addition for Purim that begins with the words ‘Al haNissim’ (On the miracles).. Approximately an average slice of bread would be the minimum requirement for saying the Grace after Meals. Of course, it is desirable to have a fancier meal than you normally would on a weekday if possible, and it is very desirable that this meal be shared with family/friends, or at least coworkers if they are Jewish and you must be at work. It is preferable to avoid working altogether on Purim. Monetary gifts should be given to the poor on Purim and if you are not going to be in a place where you meet needy people, you can delegate someone else to fulfill this mitzvah for you. Often the gabai or Rabbi of the synagogue performs this service for the congregants. If this is also not possible, you can set aside money on Purim for the needy and make sure to get it to them as soon as possible.
Mishloach Manot, known colloquially as “Shlachmones”, are gifts we are to give to at the very least one friend of the same gender, and they are comprised of at least two different items of food which would require two separate blessings, and some have the custom to include a drink as well, which could be wine, fruit juice or other. The reason for this is that Mordechai and Esther instituted this in the Megillah, to increase rejoicing and foster love and goodwill between people. The gifts should preferably be sent through a third party, which can easily be arranged by asking someone to pass the package to the person you designated it for.
At the Minchah service (the afternoon prayers) before Purim, there is a practice of contributing ‘Machatzit haShekel’, a half shekel coin, but three of them, for each person in the family, to be contributed to charity. In Israel the coin is the shekel, but the custom is based on the value of the Biblical shekel. Some have the practice to contribute corresponding to the value of three Biblical half shekels, while others in Israel have the custom to use current half shekel coins. You should follow the practice of your community, or the nearest orthodox Rabbi or Chabad emissary.
The main thing is that Purim should be a time of joy, when we internalize the very special messages of the Purim story. Although the name of G-d is not mentioned at all in the Megillah, the way the story unfolded is miraculous, and this teaches us that the hand of G-d is at work even when it may not be obvious at the time. By turning away from secular influences and returning wholeheartedly to G-d’s Torah and ways, the Jews merited to have the evil decree of Haman averted, and also completed the Jewish people’s acceptance of Torah that had begun at Sinai.
Mordechai and Esther bequeathed us a legacy of loyalty to G-d and the Torah, as well as our fellow Jew.