Fox plans to announce officially that Conan O'Brien will be joining the network at its annual upfront presentation to advertisers on May 17, reported that while O'Brien is racing across the country with his one-man show, "Legally Prohibited From Being Funny on Television Tour," he has left open the May 17 date. Fox still has its affiliates to appease, some of whom are doing quite nicely during the late-night hours with syndicated features.