I’ve been working with Backbone for approximately a month now. I’m a fan of using a structured coding practice to untangle your objects and the DOM.
In Backbone, you get the latest state of your model by fetching it from the server. You can set a callback on the fetch function directly or by binding to the collection’s reset event.

I needed to fetching more than one collection at the same time and call a callback when all of the fetches were finished.