UPDATE: Please read this again and keep a printed copy with you at all times.
Rav Kanievsky Shlit"a said to be ready to say the blessings when Mashiach arrives (The Rav has periodically spoken about Mashiach). If Rav Kanievsky Shlit"a happens to be Eliyahu HaNavi, and he announces "who" Mashiach is, the following are the Brachot to be said IY"H [written in a sequence depending what happens first, second, etc.]
When we first hear from a reliable source the good news of Moshiach’s arrival, we will recite
- “Baruch Attah Hashem Elokeinu Melech HaOlam HaTov V’HaMeiteiv.”
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 Attah Hashem Elokeinu Melech HaOlam chacham harazim.”
When one sees the rebuilt Beis HaMikdash or rebuilt shullen or Batei Medrash, one recites,
- "Baruch Attah Hashem Elokeinu Melech HaOlam matziv gvul almanah.”
When we actually see the Moshiach, we will recite
- "Baruch Attah Hashem Elokeinu Melech HaOlam She’chalak Mikevodo Li’rei’av."
Immediately after reciting this bracha, we will recite the bracha
- "Baruch Attah Hashem Elokeinu Melech HaOlam She’chalak Meichachmaso li’rei’av."
And the following Shehechiyanu and Go'el Yisrael:
*For a deeper explanation of these Brachot, and about Mashiach, visit When Moshiach Comes at Yeshiva.org.il by Rabbi Yirmiyohu Kaganoff