Need help with setinterval

Hello!
I want to do a small delay for just a couple of frame between each duplicating in the script below. Can you show me how to do this? Is there any easier way than using setinterval? I have tried using setinterval but I don’t understand how to do it. Please help me with this or show me another way to create timing with actionscript…

function makeItems() {
button._visible = 0;
for (var i = 0; i<item.length; i++) {
// I want a delay between each loop!
var btn = button.duplicateMovieClip(i, 100+i);
btn.id = i;
btn._x = button._x+(i*30);
btn.onRelease = function() {
firstImage(this.id);
};

}
}