functions.php

<?php
// Add a date range to a datepicker field, replace #date with the id of the date field.
add_filter( 'wp_footer' , 'woo_add_checkout_field_date_range_limit' );
function woo_add_checkout_field_date_range_limit() {
    if ( is_checkout() ) {
        $js = 'jQuery( "#date" ).datepicker({ minDate: -5, maxDate: "+1M +10D" });';
        // Check if WC 2.1+
        if ( defined( 'WC_VERSION' ) && WC_VERSION ) {
            wc_enqueue_js( $js );
        } else {
            global $woocommerce;
            $woocommerce->add_inline_js( $js );
        }
    }
}
?>