If it's on your blog and easily accessed by anyone, we consider that published. (A private group might be a different story.) But if you published it on your blog after it was published by us, that wouldn't be a problem. We state that we do not consider previously work on our guidelines page. But other journals have other policies. You can check the "Previously Published OK" box on the Chill Subs Browse page to get a list of journals that accept previously published work.