This is actually from another blog, but I thought it was great information!
This post is how to change the date and time of a post to suit your needs...when you have the free time to write! Are you so busy during the week that you can't post when you want to? Is Friday or Saturday easier for you? Maybe you have a day off during the week where you could write several posts. Let me show you how to change the date and time of each of your posts, so you can write them all on one day and they will post throughout the week...when you want them to!
Write your post as usual. When you are done, click on the bottom left button called "Post Options". I have it circled in black below. Click on the picture to enlarge.
A drop down option will appear. In the section on the right, that I have circled in black, you can change the date and time of when you want the post to be published. Make sure you keep it in the same format that it's written in. For example...month/day/year...3/27/11 and AM or PM
When you are finished, click the "Publish Post" button circled in black on the bottom left. It won't publish at that time, but it will be stored in your edit post list until the date you picked.
Go to your edit post list and you will see it as "Scheduled" with the future date and time you have chosen.
Another thing you can do with the time date feature is to republish an old post.
If you are editing a post, but want to keep it on the same date, just make you corrections in the post and publish again. The changes will be made, but it will still post on the original date.
However, if you want to edit a post and republish it new again...bring up your old post, change the date and hit "Publish Post" again. That old post will be published on that new date.