On Avodah, Saul Newman gave the following summary of halakhos related to bi’as hamashiach from an article in the Yated. I found that the pragmatic halachic discussion gave some mamashus (tangibility) to the idea.
In conclusion, we may recite a total of eight special brachos when Moshiach arrives, in the following order:
- When we first hear from a reliable source the good news of Moshiach’s arrival, we will recite Baruch Atah Hashem Elokeinu Melech Ha’olam hatov vehameiteiv.
- When we see the huge throngs of Jews assembled to greet him, which will no doubt number at least 600,000 people, one recites, “Baruch Atah Hashem Elokeinu Melech Ha’olam chacham ha’razim.”
- When one sees the rebuilt Beis Hamikdash or rebuilt shuls or batei medrash, one recites, “Baruch Atah Hashem Elokeinu Melech Ha’olam matziv gevul almana.” Theoretically, one might recite this bracha before the bracha Chacham ha’razim, if one sees the rebuilt Beis Hamikdash before one sees the huge throngs.
- When we actually see Moshiach, we will recite, “Baruch Atah Hashem
Elokeinu Melech Ha’olam shechalak mikevodo lirei’av.”
- Immediately after reciting this bracha, we will recite the bracha, “Baruch Atah Hashem Elokeinu Melech Ha’olam shechalak mei’chachmaso lirei’av.” According to some poskim, one may recite these last two brachos when aware that Moshiach is nearby, even if one cannot see him.
Michael Kopinsky noted on this item that it presumes that the melekh hamashiach will be a rabbinic figure as well as king. This was true for our greatest kings — David and Shelomo — but it is not a prerequisite for the job. As he asks, “Was Bar Kochva, for example, eligible for the bracha of shechalak meichachmaso?” and yet that didn’t prevent Rabbi Aqiva from deciding Bar Kochba qualified to be mashiach.
- When one actually sees Moshiach, one should recite Shehechiyanu.
- , 8. According to the Lev Chaim, on the anniversary of Moshiach‘s arrival, we will again recite Shehechiyanu to commemorate the date, and we will recite a long bracha mentioning some of the details of the miraculous events of his arrival. This bracha will close with the words, Baruch Atah Hashem Go’al Yisroel.