Firstly, launch Outlook application.
Then turn to “Calendar” pane and click “New Meeting” button.
Next in the opened “New Meeting” window, you can compose the meeting as per your needs.
After that, you should hit “Forward” button in ribbon and select “Forward as iCalendar” from the drop down list
At once, a new email will turn up and the meeting item has been inserted as an attachment. Now you can compose the email.
Finally you can shift to “Options” tab and click “Delay Delivery” button to set a specific time for sending the email.
When this email is sent out at its scheduled time, the recipients can double click on the attached meeting item to make responses.