You can add a single open time or complete these in bulk for a number of properties.
To create a single open you can do this from the quick add button or on the listing itself.
From the Quick Add
Click quick add
Open for Inspection
From the Property
Navigate to the listing details page, and click on the Open Time widget click the ellipsis and select + Open Insp
You can also navigate to the module in your menu called Multiple Opens, which will allow you to complete multiple times and properties in one spot.