jquery : how to fix quick sliding?

jquery : how to fix quick sliding?

I have build a slider using jQuery which works fine except a small issue.
The slider moves quickly before the present one complete its move.
Especially the second and third slide move have the issue
Does any one have solution or alternative to fix this issue ?
$.fx.speeds._default = 1000;
function slider(container) {
var currPg = null,
firstPg = null;
container.find('> *').each(function (idx, pg) {
pg = $(pg);
var o = {
testimonial: pg.find('> .testimonial'),
thumb: pg.find('> .testimonial-thumb'),
pg: pg
};
o.pg.css({
position: 'absolute',
width: '100%',
height: '100%',
});
if (idx > 0) {
o.pg.css({
opacity: 0,
'z-index': -1
});
o.testimonial.css({
'margin-left': '100%'
});
o.thumb.css({
'bottom': '-100%'
});
} else {
firstPg = o;
}
o.prev = currPg;
if (currPg) {
currPg.next = o;
}
currPg = o;
});
firstPg.prev = currPg;
currPg.next = firstPg;
currPg = firstPg;
this.advance = function advance(duration) {
console.log("advance!", this);
var dur = duration || $.fx.speeds._default;
var dur2 = Math.ceil(dur / 2);
var dh = container.height();
var dw = container.width();
var nextPg = currPg.next;
nextPg.pg.css({
opacity: 1,
'z-index': null
});
var _pg = currPg;
currPg.testimonial.stop().animate({
'margin-left': -dw
}, dur, function () {
_pg.pg.css({
opacity: 0,
'z-index': -1
});
_pg = null;
});
nextPg.testimonial.stop()
.css({
'margin-left': dh
})
.animate({
'margin-left': 0
}, dur);
currPg.thumb.stop().animate({
'bottom': -dh
}, dur2, function () {
nextPg.thumb.stop()
.css({
'bottom': -dh
})
.animate({
'bottom': 0
}, dur2);
nextPg = null;
});
currPg = nextPg;
}
}
var s = new slider($('#banner'));
function scheduleNext() {
setTimeout(function () {
s.advance();
scheduleNext();
}, 5000);
}
scheduleNext();
Demo http://jsfiddle.net/sweetmaanu/Pn2UB/13/