Is this the proper usage of creating / using a transient?

No quite: Get the transient’s content first, then do the expensive work to fetch the external resource.

function google_transient() {
    $transient_name="google";
    $content        = get_transient( $transient_name );

    // done
    if ( $content )
        return $content;

    $url="http://www.google.com";
    $content = wp_remote_retrieve_body( wp_remote_get($url) );

    set_transient( $transient_name, $content, DAY_IN_SECONDS ); // 24 hour cache          

    return $content;
}