One simple way of creating fetch fast is to use advanced find and render that fetch in javascript.
Open advanced find and reopen window by pressing CTRL-N

Create your query...dont forget to build your query in full-window not framed as in screen shoot

Replace your URL with one of below javascript calls

        javascript:alert(resultRender.FetchXml.value);

javascript:document.writeln(resultRender.FetchXml.value);

Now view source for fetch command

Copy and past and insert in your callouts or what ever your building

The result when prompting (alert) advanced find query