If you need to get first index or key from array then you can use simple php function key. This is simple code which give you first key from array.

<?php
$data = array(
    14 => "Test14",
    11 => "Test11",
    4 => "Test4",
    12 => "Test12",
    13 => "Test13");
echo "<pre>";
print_r($data);
reset($data); // reset — Set the internal pointer of an array to its first element
$first_key = key($data); //key — Fetch a key from an array
echo "First Key: ".$first_key;
?>

then result is:

Array
(
    [14] => Test14
    [11] => Test11
    [4] => Test4
    [12] => Test12
    [13] => Test13
)
First Key: 14

If you need any help then please inform me, i will try to help you.