Theoretically, the alternate timeline was created when the Island gets destroyed in 1977. But there are so many people who SHOULDN'T be in this alternate timeline if that was the case. Pierre Change, Ben, Ben's Father, Eloise Hawking, Charles Widmore, Daniel Faraday, and Penny should all not exist in this timeline. With that said, I have a hard time to believe that this is just a mistake, because while the writers do make continuity errors (they are human) they are in general minor ones that don't really matter. This would be a MAJOR mistake, if it is in fact one. Thoughts?