The media-carrying book for the Collector's Edition of The Cutting Edge reproduces both sides of the release card for Record 1 of Blonde On Blonde. The front of the card gives the Shipping Date as 5-16-66, and the rear of the card date of the card is dated 4-27-66.  In other words, on April 27th, when the card was prepared, the projected shipping date was May 16th.  This date was still being cited as the release date by Sony in 2010, when they printed it in the booklet for the Original Mono Recordings box set.

Release card for Blonde On Blonde, front

Release card for Blonde On Blonde, back