Javascript - banner rotation random start

LP!

Imam naslednjo skropto:

var used = 0;
var location_counter = 0;
var refresh_counter = 1;
var map = new Array();

function banner(a, b, c, d, e) {
	this.name = a;
	this.url = b;
	this.image = c;
	this.date = d;
	this.active = 1;
	this.oid = 0;
	if (e != '') {
		this.loc = e
	} else {
		this.loc = settings.default_ad_loc
	}
}

function show_banners(a) {
	location_counter = location_counter + 1;
	if (a != '' && a != undefined) {
		map[location_counter] = a
	} else {
		map[location_counter] = settings.default_ad_loc
	}
	var b = '<div id="' + settings.location_prefix + location_counter + '" class="' + settings.location_class + '"></div>';
	document.write(b);
	display_banners(location_counter)
}

function display_banners(a) {
	var b = new Array();
	if (a == '' || !a || a < 0) {
		return
	}
	var c = banners.length;
	if ((c == used) && settings.duplicate_banners == 0) {
		return
	}
	for (i = 0; i < (banners.length); i++) {
		banners[i].oid = i;
		if ((banners[i].loc == map[a]) && (banners[i].active == 1)) {
			b.push(banners[i])
		}
	}
	var d = Math.floor(Math.random() * b.length);
	var e = b[d];
	var f = (settings.force_size == 1) ? ' width="' + settings.img_width + '" height="' + settings.img_height + '"' : '';
	var g = '<a href="' + e.url + '" title="' + e.name + '" target="' + settings.window + '"><img border="0" src="' + e.image + '"' + f + ' alt="' + e.name + '" /></a>';
	var h = new Date();
	var j = e.date;
	j = j.split('/', 3);
	var k = new Date();
	k.setFullYear(parseInt(j[2]), parseInt(j[1]) - 1, parseInt(j[0]));
	if ((h < k) && e.active == 1) {
		var l = document.getElementById(settings.location_prefix + a);
		if (l == null) {
			alert('spyka Webmaster banner rotator\nError: adLocation doesn\'t exist!')
		} else {
			l.innerHTML = g;
			if (settings.duplicate_banners == 0) {
				banners[e.oid].active = 0;
				used++
			}
			return
		}
	} else {
		display_banners(a)
	}
	return
}

function refresh_banners() {
	if ((refresh_counter == settings.refresh_max) || settings.refresh_time < 1) {
		clearInterval(banner_refresh)
	}
	used = 0;
	for (j = 0; j < (banners.length); j++) {
		banners[j].active = 1
	}
	for (j = 1; j < (location_counter + 1); j++) {
		display_banners(j)
	}
	refresh_counter++
}
var banner_refresh = window.setInterval(refresh_banners, settings.refresh_time);

Če prav razumem, omenjena koda prikazuje vse bannerje v random zaporedju? Math.random se kliče vsakič, ko se zamenja banner?

Kam naj prestavim random funkcijo, da se bo zagnala samo, ko uporabnik prvič odpre stran. Se pravi, da začne rotirati bannerje na random poziciji, ampak jih potem rotira enega za drugim...

lp, Matej