If, Else inside html

I have a Django project consists of many html pages.

I want to add an if else condition inside my html tag to return "None" whenever the time stamp = 0000-00-00 00:00:00 and return the time when it's not. My code is shown below, I used a tag to get the time in date format.

<td>{{ table.start_time|date:"Y-m-d G:i:s"}}</td>