Display different post template for week old posts

Hi Guys,

I'm looking to set up single.php so if the post has been published this week it goes to currentposts.php and if older than a week then archiveposts.php, these two display the posts differently.

I can set it up so posts older than 7 days goes to archiveposts.php but I'm looking for post before Monday rather than 7 days ago.

Many thanks, Barry Reynolds