Auto-change Post Status on First Page Load

Question

If you want the default post status to be in-progress when contributors click on “New Post”, then you can try the following:

/**
 * Set default post status as 'in-progress' for contributors
 *
 * @link https://wordpress.stackexchange.com/a/143128/26350
 *
 * @param  array $data 
 * @return array $data
 */

function wpse_143100_wp_insert_post_data( $data )
{
    $current_user = wp_get_current_user();      

    if( 'auto-draft' === $data['post_status']
        && 'post' === $data['post_type']
        && '0000-00-00 00:00:00' === $data['post_date_gmt']
        && in_array( 'contributor', $current_user->roles, TRUE ) 
    )
        $data['post_status'] = 'in-progress';

    return $data;
}           

add_filter( 'wp_insert_post_data', 'wpse_143100_wp_insert_post_data' );

It’s informative to investigate the default post status transitions:

Click on “New Post”:
```
new -> auto-draft
```
Auto-Save:
```
auto-draft -> draft
```
Change post status manually to “In Progress” and then press the “Update” button:
```
draft -> in-progress
new   -> inherit (revision created)
```
Press again the “Update” post:
```
in-progress -> in-progress
```

You can hook into these transitions with the transition_post_status hook.

Update:

Here’s a modification of your example:

function educadme_assigned_to_inprogress()
{    
    global $post;
    if ( get_current_user_id() == $post->post_author  // current user is the post author
         && 'post' === get_post_type()                // current post type is 'post'
         && 'assigned' === get_post_status()          // current post status is 'assigned'
         && ! current_user_can( 'publish_post' )      // current user is 'contributor'
         && function_exists( 'EditFlow' )             // Edit flow plugin is installed
    ):
        if ( $post->ID > 0 ):
            $post->post_status="in-progress";  // use any post status
            $pid = wp_update_post( $post );      // update post             
            if ( is_wp_error( $pid ) ):          // debug
                // error_log( $pid->get_error_message(), 1 );
            endif;
        endif;
    endif;
}

add_action( 'admin_head-post.php', 'educadme_assigned_to_inprogress');

where I use the admin_head-post.php hook to narrow it down to the post screen only.

The post status will only change to in-progress if

the current user is the post author
the current user is a contributor
the Edit Flow plugin is installed
the current post type is post.
the current post status is assigned.

Notice that you will need to refresh to see the updated status.