The original plan was to start layout on the 16th. Since I do not have the full text available to edit quite yet (it should be coming soon, though), I will make sure that I've gotten all of the additional material possible written so I can get to editing right away.
Thurston is writing adventure 5. I will see him at GenCon, and so he is motivated by a desire to earn free alcohol. I expect the text will be perfectly punctual, only for us to discover that the internet has raptured itself to Lolcat heaven, forcing us to collaborate via traditional stamp-and-post.
One benefit of having different authors work on different adventures is that if we fall a bit behind, the next person should be able to keep us on schedule. I expect to maintain the current planned schedule. 4 in April (maaaybe early May), 5 in July, 6 in October, etc.