how to retrieve only the latest data

Complete novice here trying to navigate using an API to pull alerts from a swagger based api platform. I can pull the alerts fine with my api call. I am trying to develop a script that will run automatically every few mins and list the latest alerts.

The challenge I have is that it pulls down all of the present alerts which can be many thousands. What I want to try and achieve is to only pull down the latest ones since the last call.

Here some samples of valid fields.  

Any help appreciated