get_posts – get all posts by author id

I want to get all posts by certain author id (current user). Later, I want to pick the first post made by this user (ASC).
I guess I do not use the right arguments in get_posts, am I? $current_user_posts
always contains an Array with all blog posts in multiple different WP_Post Objects.

global $current_user;
get_currentuserinfo();                      

$args = array(
    'author'        =>  $current_user->ID, // I could also use $user_ID, right?
    'orderby'       =>  'post_date',
    'order'         =>  'ASC' 
    );

// get his posts 'ASC'
$current_user_posts = get_posts( $args );

I’m a bit confused. If you want to get onlya element from the posts array you can get it like this:

• reset($current_user_posts) – first post
• end($current_user_posts) – lat post

But if you want to get just one post with the get_posts() you can use the posts_per_page argument to limit the results.

$args = array(
    'author'        =>  $current_user->ID,
    'orderby'       =>  'post_date',
    'order'         =>  'ASC',
    'posts_per_page' => 1
    );

More info about parameters you can get on WP Query Class Reference page (get_posts() takes same parameters as WP Query).