A thread, or forum, or some feature of hidden gems. With the criterion being NOT a featured story in the past.
As for the original point, of a time limit on publishing, it could simply be as that. I'm writing a story currently, and have two other ideas. They have sneak preview turned off, all three, because they are in no way shape or form ready. But when they are ready to publish, I'll have sneak preview back on, so can be seen by those with interest.
tl;dr, having a restriction (or even links to another page which states why publishing a game in the first week of joining is a (little b) bad idea, and DO YOU REALLY WANT TO DO THIS?), would only serve to stop people who publish in the first week, and that's not an entirely bad thing, putting a small obstacle in the way. Can still drum up interest with sneak preview and in the forums, without spoiling it's 'first' impression, and that small window when it's most noticeable. Imho, at least. I've spent the last few days mostly getting to grips with the editor system alone. If I also needed to learn the format and structure of a CYOA, then that'd be an additional learning burden to have to carry, before being able to make a game that I'd be happy to show to anyone.