Do you mean you want the current date/time to be the default value of the control? 

If so, on your Nintex Form open the configuration of your date/time picker. Set "Default Value" to "Today"

Gives you:

Thank you Courtney. this is exactly what i was looking for.

Glad to be of assistance!

Hi again,

I need to connect this to another item but I seem to lose the default option? Is there another way to acheive both?

For dates, it seems that it disappears. For things like text boxes, you can still do it:

However, since it's connected to a SharePoint column, you can set the default of your SharePoint Column to Today's Date

Thanks again. Much appreciated.

Hi courtney_shelto, I set Today in the SharePoint Column but the time is coming as 12:00 AM, How to get current time?