The website was created on January 21.  The story seems to have broken just this morning in the Washington Post, and it is gradually being picked up by other media.  No date has yet been set, but the movement is growing literally as I type, to judge by this snippet from the Post’s article:

In short order, the march had a Facebook page (which currently has more than 200 more than 48,000 more than 150,000 members), a Twitter handle, a website, two co-chairs, Berman and science writer and public health researcher Caroline Weinberg, and a Google form through which interested researchers could sign up to help.