Megastar Amitabh Bachchan has completed over four decades of his cinematic journey and says he became an "official entrant" in Bollywood on February 15, 1969.The 74-year-old on Wednesday night wrote on his blog: "There is an avalanche of events related to this date - the 15th of February. On this date in 1969... I became an official entrant to the film industry, by signing my very first film, 'Saat Hindustani'."The "Piku" star shared a series of black and white photographs from the film's set as well. In his over four-decade journey in Bollywood, Big B worked in over 100 films and was feted with Padma Shri in 1984, the Padma Bhushan in 2001 and the Padma Vibhushan in 2015 for his contribution to arts.The government of France honoured him with its highest civilian honour, Knight of the Legion of Honour, in 2007 for his exceptional career in the world of cinema and beyond.Amitabh has worked in hits like "Bombay to Goa", "Zanjeer", "Abhimaan", "Namak Haraam", "Sholay", "Agneepath" and "Deewar".