Based on your target audience, we search for patterns in our database to display the times when we think the potential of getting more impressions with your post is the highest. The timezone is displayed is based on the one you have chosen in your settings. The heatmap recommendations will be based on when we think you should publish your post to get impressions in the location of the defined audience.
To display the color coding in your scheduling calendar, you must first choose an audience. This short tutorial video can help.
If you haven't already created an audience, I will insert some insightful help articles below:
Hope that helps!
If you have questions or other concerns, you can submit a ticket here.