You might try using the load_field hook, http://www.advancedcustomfields.com/resources/acfload_field/
You could test to see if it’s a new post and if not then set some default values based on other default values. I’m not exactly sure what you’re looking for though. If it’s a new post then wouldn’t you just use default values for these fields? Are you talking about when a new post page is first loaded or when you first publish a post?
