Draft permalinks stuffing up RSS

I’m having trouble with my draft posts relating to my RSS feed.
I like to publish posts about a particular day, on the day that they happened, but I might not write them for a few days or a week or so later. Once I go back and finish writing them, the permalink changes to the date that I finish writing them. Even if I’ve already changed ‘Published on’ date, and then when I publish the post, the permalink on the post for my journal has changed for the right day, however when it goes to my RSS feed (i.e. when it comes up on my livejournal friends page) it links to the wrong date.
So to explain my point a bit better….
the date I write it might be 2008/04/15/
The actual date I want for the post might be 2008/04/05
so when I publish it to my journal, the permalink will be 2008/04/05/post-title
but when it comes through my RSS feed it will be 2008/04/15/post-title and so the direct link from the RSS feed link brings up a 404 error, which means my friends don’t read it!
Help please? I don’t want to have this problem!!