document.write cannot be invoked after DomContentLoaded event; Since it will wipe out its content. This code rewrites document.write and allows you to inject HTML code at any time in the page.

writeFrom

(function($){
  $.fn.writeFrom = function(callback){
        var $that = this;
        setTimeout(function(){
            document.write = function(){
                try{
                    $.fn.append.apply($that, arguments);
                }catch(e){
                    console.log('INVALID APPEND', e.message);
                };
            };
         callback && callback();
        }, 0);
    };
})(jQuery);

the way you invoke the code is:

$("#myAd").writeFrom( loadMyAd );

where:

myAd: is an element where ad content will be injected.

loadMyAd: is a JS function that will eventually call document.write to inject ad content.