If you have the chrome extension installed, the "insert availability" option can be found next to the send button on the bottom of the Gmail compose window.
Insert Availability in Gmail
- Open a new compose window in Gmail or reply to an existing Gmail thread. On the top of the compose window, you'll see the chrome extension. Click the button that labeled "meetings".
- When you click on the calendar icon, an Outreach pop-up will appear, revealing your calendar.
- Select the available times in your calendar.
- Available times will be listed in date/time order.