September 10th - 1 and 2 digits
September 11th - 3 and low 4 digits
September 12th - High 4 digits (Above 6xxx) and 5 digits.
September 13th to October 21st - 6 digits
October 21st to February 18th - Email Login 7 digits (22xxxxx and below)
February 18th to Late 2005 - Username 7 digits...