Change invoice date

Hi! You can resolve this with a small code snippet. I have two flavors for you:

1) Use the completed date (this only works if this was set for those orders!)

add_action( 'wpo_wcpdf_invoice_get_date', 'wpo_wcpdf_order_date_as_invoice_date', 10, 2 );
function wpo_wcpdf_order_date_as_invoice_date( $date, $document ) {
    if ($document->get_type() == 'invoice' && !empty($document->order)) {
        if( $date_completed = $document->order->get_date_completed() ) {
            $date = $date_completed;
		}
    }
    return $date;
}

2) Use the order date (since not all orders may have a ‘completed’ date set):

add_action( 'wpo_wcpdf_invoice_get_date', 'wpo_wcpdf_order_data_as_invoice_date', 10, 2 );
function wpo_wcpdf_order_data_as_invoice_date( $date, $document ) {
    if ($document->get_type() == 'invoice' && !empty($document->order)) {
        $date = $document->order->get_date_created();
    }
    return $date;
}

If you haven’t worked with code snippets (actions/filters) or functions.php before, read this guide: How to use filters

Hope that helps!