Loading based on all subs elsewhere?

header.html

<!-- Then in your template, have a helper bound to that session variable routeLoaded... -->

<template name="header">
  <header>
    {{#if routeLoaded}}
       <p>header contents</p>
    {{else}}
      {{> loader}}
    {{/if}}
  </header>
</template>

routes.js

Router.route( 'someRoute', {
  path: '/some-route',
  template: 'someTemplate',
  subscriptions: function(){
    var subscriptions = [
      Meteor.subscribe( 'someSub1' ),
      Meteor.subscribe( 'someSub2' )
    ];
    
    // This is messy but could be replaced with a loop.
    if ( subscriptions[0].ready() && subscriptions[1].ready() ) {
      Session.set( "routeLoaded", true );
    } else {
       Session.set( "routeLoaded", false );
    }
   
    return subscriptions;
  }
});