Where to Install the main JS Code
The main Convert tracking code needs to be installed in the head section of the page, before any other loaded resource. So, after the <title> tag, is best.
It’s not an absolute requirement to install the code just after the <title> tag, but doing it this way, ensures the best performance. The reason for this is that the Convert Experiments tracking request needs to be initiated as soon as possible on the page, giving it time to get the results back before the whole page finishes loading.
Convert experiments can run even if the code is installed in the footer of the webpage. However, since the tracking request will be started just before the page has loaded, the variation changes arrive later in the browser and therefore the time that passes until the variation is visible will be longer and this can result in a visual blinking of the variation.
Where to Find your Convert JS Code
The main tracking code can be found on the Project Settings. To get to it, select your Project, on the Project Panel:
Then select on the left menu the Settings of your project that you are working on:
Then go to the lower section and click on the "<>" button as shown below.
Then copy and paste the code, and place it on your website as described in the previous section.
Regarding Google Analytics integration: If you are planning to send your experiment data to Google Analytics, make sure that the Convert tracking code is installed before the Google Analytics tracking code. Otherwise, you won't have your experiment data available in Google Analytics. Please read more at http://support.convert.com/hc/en-us/articles/205160075-Integrate-Convert-Experiments-with-Google-Analytics.