Post-dating a post (in WordPress 2.5+)
You are going away… to convention or cruise (shouldn’t we all…) and want to still post while you are gone. How about a series of posts? It’s very easy!
When you are creating a post, you may not have noticed, but in the right hand column (under Preview this Post) there is a "Publish Status" area and a choice "Publish Immediately" and EDIT (which is a link)… see first screenshot. When you click "Edit" you will get a date/time menu that you can choose.
REMEMBER: Your date/time must be properly set in >Dashboard >Settings > Also, you must click "Publish" (it will remain a draft until you hit publish).