26 years ago - Jennifer-Lynn Hayden is born the daughter of Alan Scott, and adopted. Her green skin soon develops.
13 years ago - 13-year-old Jenn takes up modeling as a part-time job.
11 years ago - 15-year-old Jenn meets her biological father Alan Scott & her brother Todd James Rice, and first discovers her Oan powers.
5 years ago - 21-year-old Jenn gets the cover of the SI swimsuit issue, but when Alan Scott dies, she retires both from modeling and from the Justice Society to become a freelance photographer.
Jade was created as part of Infinity Inc, a team based on legacy characters for the Justice Society that mirrored the Teen Titans. They were one of the incidental casualties of the first Crisis, as the shifts in realities and timeline made their current backstory impossible, but several of the characters were cool enough for the writers to put in the work to recover, and Jade was one of the best. She was simply Alan Scott's daughter, green skinned and gifted with a biological version of her father's powers. She became a supporting character for Kyle Rayner when she became a permanent house guest and later his girlfriend, but was always a well loved part of the Green Lantern legacy.
She really came into her own when she was recruited into Arsenal & Nightwing's Outsiders. She was one of the most seasoned heroes on their team, and quickly proved to be a capable back-up leader, often taking the team out on her own. She was removed from the team as it was slowly returned back to the original lineup, but when James Robinson was assembling his next generation version of the Justice League, he used Jade as his Green Lantern.
While she makes a lot of sense on the Watchtower, we prefer her in the fantastic role she played in the Outsiders.