If you are curious to find out who joined twitter first, you or your friend it can be found. This online tool whendidyoujointwitter.com takes in any user account and returns the joining date.
Now to verify this I needed another tool which came from tweet of marshallk who noticed this in Twitter for iOS, that the # right under your account name, when you click on your profile, is the account number. The lower your account number, the early you joined twitter.
