If you want to change the interval time between two notifications then, Follow the below steps.

Step: 1 => Open the ShagunBox app and choose the Sales Popup app from the side menu. 

Step: 2 => Scroll down and change the popup interval time between two notifications from Delay Between Notifications Input field.

Step: 3 => Click on the Save Settings button.

Note:  The time will be measured in Seconds.