Kibana visualization sort according to timestamp

I am using Kibana to create visualizations. I have created a count (Y axis) vs timestamp (X axis) line chart. By default it gets sorted according to the counts. But I want to sort according to timestamp. How can I do it?

Aggregations that support changing their sort order include an "Order By:" option, which you can change to sort by any of the metrics, a custom metric, or in some cases the bucket key itself