The Insightly Calendar Sync does not allow your personal events on your Google Calendar to appear within your Insightly Calendar - the events must originate within Insightly first.
The calendar sync will run approx. every 10 minutes, so any tasks, events, or milestones added to your Insightly calendar should appear on your Google Calendar shortly thereafter.
One Way or Two Way Sync
We support two flavors of sync for the calendar - either one way sync, in which a read-only version of your Insightly events, milestones and tasks are copied over to your Google Calendar - or two way sync in which items copied over to Google can be edited right in your Google Calendar, and those changes will be saved back to Insightly automatically. If you are unsure of which type to select, you should choose one way sync so you don't inadvertently make changes within Google Calendar.How to Turn On Calendar Sync
Your Insightly administrator has to first enable Google Sync for selected users. This can be done by checking the checkbox labelled 'Google Sync Enabled' for each user under Settings > Users, which can be access via the small silver gear icon in top top right corner (as shown below in Red).Once sync has been enabled for you, you can choose which sync type you want from the 'My Info' page, which is the small card icon in the top right corner (as shown below in red).
You can choose to have one way sync enabled, in which your Insightly tasks, milestones, and events will be copied to your Google Calendar, but changes made there will not be kept - or two way sync where any changes made on your Google Calendar will be copied back to your Insightly Calendar.
Below is a screenshot of Google Calendar with the three sync'ed calendars from Insightly highlighted in red.