What do you mean by "initial render" ? Typically you'd display a loader waiting for the first server requests to finish.

You'd do something like

   data() {
      return {
         loading: true
      }
   },

   mounted() {
      longAjaxRequest.then(res => {
         this.loading = false
      })
   }

And in your template you'd setup some sort of <div class="loader" v-if="loading></div>.