User blog comment:Johnnybravo44/Age of Ultron teaser gif/@comment-3048593-20130202183449/@comment-3034314-20130202233124

From what I read, it wasn't delayed just held off in favor of AvX. If I remember correct, Bendis said that he wrote it at the same time he was writing Moon Knight.

As for the wonky timeline, a believe only the first few issues (drawn by Bryan Hitch) takes place before Spidey became Superior. In interviews, Brian Michael Bendis says there's a story reason why they switch artists so feel free to speculate on that.