一次放下一个标记

I'm using Google Maps Api v3 and I'm trying to drop one marker at time on my Map, just like Google Demo but I could not get it to work, here's my code, all markers are dropped at same time.

var map;
var markers = [];

function initialize() { 
    var latlng = new google.maps.LatLng(52.520816, 13.410186);

    var options = {
        zoom: 5,
        center: latlng,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };

    map = new google.maps.Map(document.getElementById("map-canvas"), options);
}

initialize();

function loadMarkers() {  

    $.ajax({
       url: 'js/poi.php',
       type: 'GET',
       dataType : "json",
       success: function (data) {

            var latlngbounds = new google.maps.LatLngBounds();      


            $.each(data, function(index, point) {

                var marker = new google.maps.Marker({
                    position: new google.maps.LatLng(point.Lat, point.Lng),
                    animation: google.maps.Animation.DROP,
                    icon: 'img/marker.png'

                });


                markers.push(marker);
                latlngbounds.extend(marker.position);

            });

            var markerCluster = new MarkerClusterer(map, markers);
            map.fitBounds(latlngbounds);

        }

    });
}

loadMarkers();

I tried do use a Timeout on each Marker but i guess that loadMarkers(); will always drop them at once...

    setTimeout(function() {

        var marker = new google.maps.Marker({
            position: new google.maps.LatLng(point.Lat, point.Lng),
            animation: google.maps.Animation.DROP,
            icon: 'img/marker.png'

        });

    }, point.Id * 200);

Any ideas on how could I fix this ?

EDIT: The poi.php file list all points from my Table and Output them like this:

[
{"Id":"1","Lat":"52.511467","Lgn":"13.447179"},
{"Id":"2","Lat":"52.549061","Lgn":"13.422975"},
{"Id":"3","Lat":"52.497622","Lgn":"13.396110"},
{"Id":"4","Lat":"52.517683","Lgn":"13.394393"}
]