Rivers will begin the Aug. 27 evening on her 981st interview, so with all the stars gathered, she should have no difficulty meeting the mark -- perhaps within the first hour, TV Guide Channel President Ryan O'Hara said.
Rivers began reporting for TV Guide last year, but had accumulated hundreds of interviews while she was with E! Entertainment, Daily Variety reported.
The comic said she hoped her last interviewee "will be wearing a name tag."
TV Guide Channel has also contracted with Melissa Rivers, Joan Rivers' daughter, to do six hourlong episodes of "TV Candy" to give average people makeovers to look like their favorite stars.