Edit in JSFiddle

// Underscore.js implementation
var debounce = function (func, wait, immediate) {
    var timeout, result;
    return function () {
        var context = this, args = arguments;
        var later = function () {
            timeout = null;
            if (!immediate) result = func.apply(context, args);
        };
        var callNow = immediate && !timeout;
        clearTimeout(timeout);
        timeout = setTimeout(later, wait);
        if (callNow) result = func.apply(context, args);
        return result;
    };
};

var vm = function () {
    var exports = {},
        self = {};
    
    exports.items = ko.observableArray([
        "Item1",
        "Item2",
        "Item3",
        "Item4",
        "Item5"
    ]);
           
    exports.afterListRender = (function () {
        // Store stack of elements rendered
        var elementStack = [];
        
        // Handle after render
        var afterRender = debounce(
            
            // function to execute after wait time
            function () {
                
                // Debug
                console.log("After Render Debounced", elementStack);
                
                // Clear stack
                elementStack = [];
            }, 
            
            // wait time in ms                           
            80
        );
        
        // Return afterRender handler
        return function (elements) {
            /// <summary>Called after each item in the list is rendered</summary>
            /// <param name="elements" type="Object"></param>
            
            // Get list items only
            var listItems = $(elements).filter("li").get();
            
            // Add to stack
            ko.utils.arrayPushAll(elementStack, listItems);
            
            // Call debounced callback
            afterRender();
        };
        
    })();
    
    return exports;
};

ko.applyBindings(vm());

<ul data-bind="foreach: { data: items, afterRender: afterListRender }">
    <li><span data-bind="text: $data"></span></li>
</ul>