Using a Tag Manager to insert the tracking code on page does make it sub-optimal because the loading of the script will become async and therefore, will eventually load after page loads. In that way, there will be quite some time until the experiment changes can be applied.
Users can notice a flicking effect, seeing for a short time the original content which than changes into the variation content.
We do not advise on using any tag manager for inserting the main tracking code on page, but, if you want to go that route, you can. Follow the steps below:
1) grab the tracking code from your Project's settings inside your account;
2) in GTM, create a TAG of type HTML.
Paste the below code followed by the main Convert Experiences Tracking code(the one you grabbed in step 1) ) inside the tag content