On this thread we plan to gather the traditional information, new info from the Simonides 2014 conference in Vienna, and whatever we can find from, Harris A. Kalligas.
Here we have a birth date, 1818, that is earlier than the common 1820 and 1824 date.
Walsh has his first public appearance in the 1850s, however there are various involvements and publications in the 1840s.Handy-Book of Literary Curiosities (1892)
William S. Walsh
Forgeries, Literary. At the close of the year 1890 there died in an Albanian village a most remarkable character. His name was Alcibiades Simonides. He was a native of the island of Syrene, opposite Caria, where he was born in 1818. He had many accomplishments. He was eminent as a chemist, an artist, and a lithographer. His learning was profound; he was a fluent and persuasive speaker; he was gifted with extraordinary industry. Being fortunate enough to lack a conscience, he utilized all these talents by becoming a forger of ancient documents. His first public appearance was in Athens at the age of thirty-five, when he laid before the King of Greece a number of apparently priceless manuscripts. Many were works whose total disappearance has long been mourned by scholars. He gave a plausible explanation of how these documents had come into his possession. His uncle and himself had discovered them in the cloister Chilandari on Mount Athos. He was confronted with some of the most learned scholars in Athens, and satisfied them of the genuineness of his discoveries. The king ended by buying the most interesting of the lot for ten thousand dollars.
Here you can see John Elliot Hodgkin discussing the normal question of whether he was born in 1820 or 1824.
The Journal of Sacred Literature and Biblical Record, Volume 3 (1863)