It really is a challenge. Maybe you could create a small buffer of articles. The size of the buffer would depend on how often you're going to post, but enough to last you a week or two. Everything in the buffer should be ready to publish so that you can always post something interesting at the intended rate. Even if you're dead-set on posting that thing on Friday, you'll be surprised to learn how hard it can be to find the time and motivation when your servers are melting, a critical bug has been exposed in your software and you're (non-blog-writing) friends come in, swinging two cold beers in each hand.