WooCommerce Custom Date Field On Registration Form

/**
 * Snippet Name:	WooCommerce Date Of Birth Field On Registration Form
 * Snippet Author:	ecommercehints.com
 */

// Create the new Date Of Birth field
add_action( 'woocommerce_register_form', 'ecommercehints_register_date_form_field' );
function ecommercehints_register_date_form_field(){
	woocommerce_form_field(
		'date_of_birth',
		array(
			'type'        => 'date',
			'required'    => true, // Shows an asterisk if true (*)
			'label'       => 'Date Of Birth'
		),
		( isset($_POST['date_of_birth']) ? $_POST['date_of_birth'] : '' )
	);
}

// Show an error if Date Of Birth is not filled out when registering
add_action( 'woocommerce_register_post', 'ecommercehints_validate_dob', 10, 3 );
function ecommercehints_validate_dob( $username, $email, $errors ) {
	if ( empty( $_POST['date_of_birth'] ) ) {
		$errors->add( 'date_of_birth_error', 'We need to store this information to send you a birthday card.' );
	}
	if($_POST['date_of_birth'] > 2005) {
		$errors->add( 'date_of_birth_error', 'You must be born in 2006 or earlier' );
	}
}

// Save the Date Of Birth field as User Meta
add_action( 'woocommerce_created_customer', 'ecommercehints_save_dob_field' );
function ecommercehints_save_dob_field( $customer_id ){
	if ( isset( $_POST['date_of_birth'] ) ) {
		update_user_meta( $customer_id, 'date_of_birth', wc_clean( date("d/m/Y", strtotime($_POST['date_of_birth'])) ) );
	}
}

// Show Date Of Birth field in the User Editor
add_action('show_user_profile', 'custom_user_profile_fields');
add_action('edit_user_profile', 'custom_user_profile_fields');

function custom_user_profile_fields( $user ) { ?>
<h2>Custom user meta fields</h2>
    <table class="form-table">
        <tr>
            <th>
                <label for="date_of_birth"><?php _e( 'Date Of Birth' ); ?></label>
            </th>
            <td>
                <input type="text" name="date_of_birth" id="date_of_birth" value="<?php echo esc_attr( get_the_author_meta( 'date_of_birth', $user->ID ) ); ?>" class="regular-text" />
            </td>
        </tr>
    </table>
<?php
}

// Save new Date Of Birth if edited by admin
add_action( 'personal_options_update', 'update_extra_profile_fields' );
add_action( 'edit_user_profile_update', 'update_extra_profile_fields' );
function update_extra_profile_fields( $user_id ) {
    if ( current_user_can( 'edit_user', $user_id ) )
        update_user_meta( $user_id, 'date_of_birth', date("d/m/Y", strtotime($_POST['date_of_birth'])) );
}