Template subscription ready timing and dom rendering timing

I have the following (simplified for better understanding)

Please mind me if I made minor mistakes, I develop in jade and coffee so I might have made some writing the below.

{{#each items}}
<div class=".image-item">
<img src="{{url}}/>
</div>
{{/each}}
Template.onCreated( function () {
instance.autorun( function () {
sub = instance.subscribe('someSub')
if (sub.ready()) {
  Zoom()
} else {

}
})
})

Template.onRendered( function () {
  this.autorun( function () { 
     if (Template.instance().subscriptionsReady()) {
       Zoom()
     }
  })
})

I tried both, but the Zoom fires before the html inside the {{#each}} helper is done.

Zoom() grabs .image-item when it starts and document.querySelectorAll('.image-item') returns an empty array.

Am I missing something or not understanding something?