The GS program "officially" started March 01, 2003. I remember vividly as I was flying ORD-IAD on 2/28 and the "nice" GA said to another passenger the GS program doesn't start until tomorrow so no priority boarding for you until tomorrow!
The following day, I flew IAD-SFO on a 3-cabin in F and FA went around with meal choices and she came up to me last and said, what is Global Services? Is that a Lufthansa program? I said no, and explained to her this was a new invitation only program above 1K and she was very apologetic not knowing about it. She ran up front to the other FA's and went rifling through there onboard updates to find the mentioning of GS to no avail.

Needless to say, the "secret" GS program was rolled out poorly in my view as a lot of front line people didn't even know, since it was a secret.. I could tell stories around this secretive roll out from check in and other passengers complaining why does he go first etc. to GA's to FA's and even pilots handing out business cards. Some were good and but a lot were not so good.

Prior to GS, they did a trial (roughly a year IIRC) with the number (which today is the GS number) etc. called Special services and then surveyed people at the end of the period, then created GS and rolled it out on March 1st. I think the one reason for that start date was back then, your status was good until end of Feb vs today it is end of Jan. That changed from Feb to Jan after the 2009 status year where it became Jan 2010 validation as it is today some 15 years later.

BTW....I did get my meal choice which was steak, on the rare side!