models/classes/runner/time/QtiTimer.php
public function getFirstTimestamp($tags)
    {
        // extract the TimePoint identification from the provided item, and find existing range
        $range = $this->getRange($tags);
        $last = false;

        if (count($range)) {
            $last = $range[0]->getTimestamp();
        }

        return $last;
    }
public function getFirstTimestamp($tags)
    {
        // extract the TimePoint identification from the provided item, and find existing range
        $range = $this->getRange($tags);
        $last = false;

        if (count($range)) {
            $last = $range[0]->getTimestamp();
        }

        return $last;
    }
Gets the first timestamp of the range for the provided tags
@param string|array $tags
@return float $timestamp