It will be completely flicker-free and work correctly. For more insights into how to leverage the utag.sync.js template, please reference implementing synchronous code within TiQ using utag.sync.js.
Grab your Convert tracking code
Make sure you have the Convert tracking code.
Ensure utag.sync.js is enabled
See the article on Publish Configuration and Generate utag.sync.js. It is just a simple case of enabling this and then saving your latest version.
Open the utag.sync template and add your code
You will now be able to access the utag.sync.js template in the templates drop-down (see this article for how to access the templates) and paste in the Convert tracking code at the bottom.
Save and Publish
Go ahead and 'Save Profile Template' and then publish the version! You are now live.