";
    
    //D-M-Y formate   
    $date2 = "24-09-2020";
    $timestamp2 = strtotime($date2);

    echo $timestamp2; 
    echo "
";
       
    //British English words Formate
    $date3 = "16 May 2019";
    $timestamp3 = strtotime($date3);
    
    echo $timestamp3;

?>

//Output:
1600819200
1600905600
1557964800