I have the complete TV broadcast of Super Bowl 3 on video. The announcers call it the 3rd annual Super Bowl.
Plus all the reports I've seen (including the one I copied & pasted for the answer) about the "super ball" story say that 1969 and Super Bowl 3 was when the term was 1st used.
Here's an auction for a Super Bowl 3 program:
http://cgi.ebay.com/1969-Super-Bowl-III ... dZViewItem
It says Super Bowl on the cover.
Here's the link where I got the answer from:
Here's a copy & paste directly from that link:
The Super Bowl was created as part of the merger agreement between the National Football League (NFL) and its rival, the American Football League (AFL). After its inception in 1920, the NFL fended off several rival leagues before the AFL began play in 1960. The intense competitive war for players and fans led to serious merger talks between the two leagues in 1966 (See AFL-NFL Merger for more information).
One of the conditions of the agreement was that the winners of each league's championship game would meet in a contest to determine the "world champion of football". During the discussions to iron out the details, AFL founder and Kansas City Chiefs owner Lamar Hunt had jokingly referred to the proposed interleague championship as the "Super Bowl." Hunt thought of the name after seeing his daughter playing with a toy called a Super Ball. The ball is now on display at the Pro Football Hall of Fame in Canton, Ohio. The name was feasible because postseason college football games had long been known as "bowl games" (The term originates with the Rose Bowl game, which was in turn named for the bowl-shaped stadium in which it is played). Hunt only meant his suggested name to be a stopgap until a better one could be found. Not having thought of one, the owners named the contest the NFL-AFL World Championship Game. Unsurprisingly, fans and media tended to use the shorter, unofficial name. Starting with the third contest in 1969, the name "Super Bowl" became official.]
I'm 100% sure that I got this one right.