I was on 02 at night starting in Sept 2003. I was evaluated in December 2003 and listed in January 2004. I started using 02 "full time" in August 2004. I was transplanted in November 2004. I used full time very loosely. In hindsight i should have had the 02 on at all times. When we would go out in public, i would leave the 02 in the car, and put it back on right when we got in the car. i had it on anytime we were in teh apartment and when i went to the gym. Always when i slept. But i was very stubborn about it and never wanted to wear it in public. So i should have had it on full time, but i refused. Not very smart and i don't suggest that sort of behavior!!!