From Gmail
When you open a Google Calendar invite in Gmail, you’ll see a new More Options dropdown menu, allowing you to propose a new time for the meeting or add a note to your RSVP.
Selecting either option will open the respective event section in calendar.google.com, where you can make those updates directly. You cannot propose a new meeting time if you are the organizer of the event. If you are the organizer, you can simply edit the event time from Google Calendar.
From Google Calendar
This feature is also available directly in Google Calendar. Simply navigate to Google Calendar and after logging in, select the event that you wish to propose a new time. Once you have clicked on the event, you can simply select the drop down menu button at the bottom.
There, you will be able to select either Propose a new time or Add note.
