(written from a Production point of view)
Text from "It's Federation Day!" states that Ambassador T'Jan was the Vulcan representative at the Federation Charter signing ceremony on October 11, 2161. At the conference she said, "Following the end of your world's war with the unseen Romulan enemy, such a union as we create here today is the most logical course of action any of our peoples can take."
The article containing this information was included in the Picard family album during the filming of Generations. However, the information is non-canon as the article was never seen on-screen. T'Jan was named for Larry Nemeceks wife Janet.