$filename = 'calendar.csv'; 
$period   = 6; 
$fields   = array('Месяц', 'Встреча', 'Тестирование'); 

$fh = fopen($filename, 'w'); 
fputcsv($fh, $fields); 

for ($i = 0; $i < $period; $i++) { 
    $month = date('F Y', strtotime("$i month")); 
    $meeting = strtotime("14 $month"); 

    if(in_array(date('D', $meeting), array('Sat', 'Sun'))) 
        $meeting = strtotime('next monday', $meeting); 

    $testing = strtotime("last day of $month"); 

    if(in_array(date('D', $testing), array('Fri', 'Sat', 'Sun'))) 
        $testing = strtotime('previous thursday', $testing); 

    fputcsv($fh, array($month, date('d', $meeting), date('d', $testing))); 
} 

fclose($fh);