There seems to be conflicting information. Sounds like they had orders lined up in 2005. One source says industrial launch was on 6 October 2005, another says

There seems to be conflicting information. Sounds like they had orders lined up in 2005. One source says industrial launch was on 6 October 2005, another says final approval for the launch got delayed to 2006. All a bit ambiguous. But in any case, it looks like Airbus has a similar development timeline for new planes that Boeing does. I suspect that is broadly applicable to other manufacturers as well. As a sanity check, I looked at the development of the smaller airliner from Bombardier (now Airbus A220) and it was January 2007 for industrial start, to September 2013 for maiden flight.