Mars by 2024, so immediately 2 years after the first Red Dragon, I guess they're gonna just send a few dozen at once? Damn.
The video where he talks is here, don't mind the thumbnail, this was a unoffical reupload. But I don't know where he said it so here! Article! http://www.cnbc.com/2016/06/02/musk-we-intend-to-launch-people-to-mars-in-2024.html