Disable textfield if not empty in cq dialog

I want to call a JS function on load of cq dialog to validate if a field already has something, if so, disable it from edition. I have tried with validation but it is called after the users interacts with the field, I need a way to do it before, when is being loaded. It is possible?

<id
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/coral/foundation/form/textfield"
   fieldLabel="ID"
   validation="is_empty"
   name="./id"
   required="{Boolean}true"/>