The longest gap between a tweet being tweeted and then retweeted will shortly pass the five year mark, when someone sometime after 9.50pm PST will RT the first ever tweet from Jack Dorsey, or @jack, Twitter Chairman and author of “just setting up my twttr”. You saw right; in its early iteration twitter lacked vowels, and also sported a very natty logo IMHO. Most of the first tweets all said the same thing as they were automated tweets issued as the launch team all got their accounts up and running.
The very observant will note that the URL for the tweet is http://twitter.com/#!/jack/status/20 suggesting that there were 19 earlier tweets but as it appear that the @jack account was the first it’s more likely the URLs were used in testing. The first real human generated tweet also from @Jack was “inviting coworkers”.