Make pop-up open after a while

Use setTimeout and show the popup with .fadeIn() , like this:

if($('.popup-banner').length > 0) {
    (window.location.href === '/')

    setTimeout(function(){
       $(".popup-banner").fadeIn();
    }, 3000); // 3000 = 3 segundos

    $('.popup-banner .fechar, .popup-banner .link-fechar, .popup-overlay').click(function() {
        $('.popup-overlay, .popup-banner').fadeOut(400);
    });
}

Example:

if($('.popup-banner').length > 0) {
    (window.location.href === '/')
    
    setTimeout(function(){
       $(".popup-banner").fadeIn();
    }, 3000); // 3000 = 3 segundos
    
    $('.popup-banner .fechar, .popup-banner .link-fechar, .popup-overlay').click(function() {
        $('.popup-overlay, .popup-banner').fadeOut(400);
    });
}

.popup-banner{
   display: none;
   background: red;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>Aguarde3segundos...<divclass="popup-banner">
   pop up
</div>

I just kept what will make the element open:

setTimeout( function() {
   $('.popup-overlay, .popup-banner').fadeOut(400);
},3000)

This causes the click function to stop working, since the idea is to open it automatically.

If you want to keep the click, keep your existing code (which only deals with the click) and add this new one, which will do the same thing, however considering ONLY the time.

Note that 3000 is the time in milliseconds.