We have no "offical" time that we won't accept submissions. However, the sooner the better as I still have to build the method of voting and everything else to get the stuff ready. Even if its a rough draft that people can understand what you are trying to do, these don't have to be final versions and most likely we will still have you do some changes to it so it fits perfectly in the forum.
If you are using photoshop or anything else that has layers, try to keep the layers seperated as we can use other elements for different parts of our style.