When Would Diane Take Over WNT?

If TMZ and Roger Friedman (and earlier, B&C) are right, and Diane Sawyer is moving to World News Tonight, when is it happening?

Friedman says: “Diane and ABC are so desperate to steal Katie Couric‘s thunder that they will get her in the anchor chair very quickly. Katie is still under contract to NBC, and can’t even begin negotiations until May 15. By that time, Diane — who’s been rotating with Gibson — could be settled in on a permanent basis.”

And an anonymous tipster wrote yesterday: “Word around 147 Columbus is that Diane Sawyer will go to WNT and that an announcement will be made this week.” (147 Columbus is next door to the newsroom on West 66th.)

But how could the move be made so soon? How could ABC spin it? Elizabeth Vargas won’t be on maternity leave until the summer…