Trim posts from WP-Query?

I think it would be better to just do a second query if you don’t have 8 posts for that month, for example:

//get current date
$date = getdate();

//setup args
$args = array(
    //basic stuff
    'posts_per_page' => -1,
    'post_stutus'    => 'publish',
    //time parameters
    'year'           => $date['year'],
    'month_num'      => $date['mon']
);

//create WP_Query
$my_query = new WP_Query;

//execute first WP_Query
$posts = $my_query->query( $args );

//check first WP_Query, update if necessary
if( count( $posts ) < 8 ) {
    //update args
    unset( $args['year'] );
    unset( $args['mon'] );
    $args['posts_per_page'] = 8;

    //do query
    $posts = $my_query->query( $args );
}

//do your loop and such

That’s some rough code that I just banged out real fast, but you get the idea