Entering data for previous day into correct folder

I am trying to backdate some posts, but I’m having some problems entering them properly.

My url filename structure it:

Url/year/month/date/title

So for instance I want to enter a post and backdate it for January 7th, so it looks like this:

Url/2010/01/07/title

But no matter what I do, the url ends up with today’s date looking like this:

Url/2010/01/10/title

Any clues? I need the correct date in the url for a program I’m working on to operate properly. Thanks!