CBS’ “The Early Show” will be broadcast in high definition beginning Monday morning. “Early” is the last of the three broadcast morning shows to go HD. For the next few months, the show’s production staff will use the “Evening News” control room at CBS News headquarters on West 57th Street. That’s about a mile across town from where “Early” originates at the General Motors building on Central Park South and 5th Ave. “The Early Show” HD control room should be ready by late summer.