Here’s a quick tip in response to a query in Twitter by Riccardo Mares. By making a small change to the Google Tag Manager container snippet, you can have the <script> element generated by the snippet notify the page as soon as the Google Tag Manager library has downloaded.
What you do with this information is up to you. If you are working directly with the google_tag_manager interface, for example, it might make sense to not act until the interface has been established.
For some reason, you might run into a situation where you need to add multiple Google Tag Manager containers on the same page. Usually this is because of poor governance or an inflexible organization. My recommendation is to fix things in your projects first, and only resort to multiple containers if you can’t seem to resolve your governance issues using your vocal cords (or your fists).
Officially, Google Tag Manager introduced support for adding multiple containers earlier in 2015.
If you haven’t lived in a barrel, you should know by now that a new version of Google Tag Manager has been released. You can find the new version at http://tagmanager.google.com/, and there’s already a bunch of good articles about the new UI out there. I want to point out two: “Setting up GA via GTM’s new UX” by Krista Seiden, and “Google Tag Manager Refresh – 6 Things You Need to Know” by Jonathan Weber from Bounteous.