You can set a future date for a post to be published, or you can change the date of a post that is already published (although not recommended, as it will result in dead links, particularly in search engines).
In Blogger, it has a post date option.. Makes it very easy to catch up with last-weeks posts if you miss them.. I can choose a two-month-old pic from flickr and create a post from the day the pic was taken, not today..
I’m trying to re-build my blog, and have posts that will go back several years.. Without being able to specify a post date, everything will be random and out of order..