woocommerce first order coupon

//Just include it to your functions.php
// VALIDATE YOUR COUPON CODE FOR THE FIRST ORDER ONLY

add_filter( 'woocommerce_coupon_is_valid', 'woocommerce_coupon_first_order', 10, 2 );

function woocommerce_coupon_first_order( $true, $instance ) {
    if ( ( $instance->code != 'COUPONCODE' ) || ! is_user_logged_in() ) return $true;
    $customer_orders = get_posts( array(
        'meta_key'    => '_customer_user',
        'meta_value'  => get_current_user_id(),
        'post_type'   => 'shop_order',
        'numberposts'=> -1
    ) );
    $true = count( $customer_orders ) > 0 ? false : $true; 
    return $true;
}