According to the Game Show Congress 6 program (which was reprinted from a New York Sunday News article on 8/5/73), the chronology was this:
--Before the pilot, the exec runthrough was at the Americana Hotel (now the NY Sheraton on 7th Ave. and 52nd.) In the article mentions the winners' circle as we know it today was part of the runthrough. That will conflict with some of the points below.
--Pilot taped (presumably February 2, 1973). This is 7 weeks before the premiere.
--Stewart mentions after the pilot that he got a call on a Monday (doesn't mention which week) that they like the Pyramid, but don't like the main game.
--The next day, he had a runthrough for a different show scheduled with Bill Cullen and Peggy Cass, they did the revamped Pyramid runthrough instead. This was done live with CBS execs in the room.
--After the conference, they told Stewart to now change the end game, since it doesn't mesh with the new front game.
--On Thursday, they did the run through that had both parts in place.
--It was picked up the next day.
And my commentary/other research notes:
--First item I see in a news article about the show is February 21. It mentions the show as "The $10,000 Pyramid" instead of the "Cash on the Line" title of the pilot. No mention is made of host.
--References to Dick Clark as host do not start appearing until March 15.
--TV listing references to the show state "10 categories in 60 seconds"
--The first episode taped March 22.
--I have seen the picture Matt is referring to, and no I don't have a copy either. That picture has 15 boxes on the winners' game board (no circle yet) and probably what would have been the worst color scheme/set in history.
--Based on the picture, and knowing that Bob Stewart never let a concept die, I would place a small wager on the original end game being like the Pass the Buck end game.
Unrelated but a interesting nugget:
The original title of Jackpot! was Bank-O
No copy of the pilot has been found, and the two quickie runthroughs were done without cameras. It's a little frustrating that of all of the Bob Stewart pilots, this is the one that is currently vaporware instead of the 18th variation of Shoot the Stars.