Trying to create thumbnail of a zencoder / s3 video

Question

Whenever I run my code to generate the thumbnail it is generating a thumbnail of the beginning of the video, even if I put some time in the middle of the video

$body = [
        'input' => $inputUrl,
        'outputs' => [
            [
                'thumbnails' => [
                    [
                        "label" => "first",
                        'base_url' => $outputUrl,
                        'number' => 1,
                        'times' => [20],
                    ],
                ],
                'notifications' => [
                    'url' => "{$notificationUrl}",
                    'format' => 'json',
                ],
            ],
        ],
    ];