Enabling permalinks outside admin

I am trying to set permalinks to a custom structure without requiring the user login as admin.
I wrote a small plugin as given below

add_filter(‘init’, ‘my_rewrite_rules’);
function my_rewrite_rules() {
global $wp_rewrite;
$wp_rewrite->set_permalink_structure(‘/%year%/%monthnum%/%day%/%postname%/’);
$wp_rewrite->flush_rules();
}

The permalink structure is changed and the links now reflect the right structure; However .htacess is not updated and I get a 404 page not found.

I have searched a lot for a solution but it seems that the only way to make $wp_rewrite->flush_rules write to .htacess is as admin or by using an admin hook (e.g. admin_init). But I need .htacess to be written without going in as admin.

I found that an action called permalink_structure_changed is created by set_permalink_structure() but adding an action to that hook also didnt work.

Any help would be greatly appreciated.