I instructed for two and a half years (part time) prior to starting class with Air Wisconsin in January 2006. I got my CFI in April 2003 as a sophomore in college and didn't graudate until December 2005 due to my co-op with UPS. I instructed full-time during the summer of 2003 and 2004, and part time during the semesters at college and part time while working at UPS.
When I started class at AWAC, I had my CFI-AIM and somewhere in the ballpark of 700 hours dual given.