Just in case you still want to post to a previous topic, you can still do so. Here are 2 things you might not know about Blogger that can help.
1. If you click "Show All" next to the blank box at the bottom of the box for composing posts, it will show the labels for the various prompts we have had. Select the one to which your submission belongs. This helps anyone wanting to look at all of the submissions relevant to the topic label. Even if you are posting on time, it would be helpful if you could do this.
2. Also on the bar at the bottom of the compose box, there is a link called " Post Options". If you click on that, you will see Post date and time to the right. You can back date your post so that it falls within the time period for the topic to which you are submitting. So, if you want your submission on "Winter White" to show up with the others of that time period, you can alter the date to be the date preceeding the start date for the following prompt. (If you don't understand, just email me.)
It doesn't necessarily apply to this blog, but you can actually post in advance of the date or time you wish your posts to appear, as well. You just have the change it to be the date or time you want the post to appear. When you have composed the post, click publish post - as usual. It will take you to the edit post page and show that the post is scheduled to appear. A useful trick if you are going to be away!
Looking forward to seeing what you are working on whenever you want to show it!