Delegate calendar access

To delegate your calendar:

1. Sign in to your calendar at http://calendar.google.com/a/your_domain.com.
2. From the gear menu, select Settings.
3. Click Calendars.
4. In the Sharing column for your calendar, click Share this calendar or Shared: Edit settings (whichever appears).
5. In the Share with specific people box, type the email address of the person to whom you want to delegate your calendar.
6. Click Add Person.
7. In the drop-down box under Permission Settings, select Make changes AND manage sharing.
8. Click Save.

After you've delegated your calendar, your delegate can sign in to their calendar and manage your calendar. For example, your delegate can follow these steps to create a new event on your calendar:

1. Sign in to Calendar (the delegate's calendar).
2. Verify that the delegated calendar shows up in the My Calendars list.
3. In the drop-down list by the delegated calendar, select Create a new event on this calendar.

If a user named Carol delegates her calendar to her administrative assistant named Jim, and Jim creates an event on Carol's calendar, the event will show up on Carol's calendar as Created by: Jim. Invitations to the event will come from Carol. On the invitation, Carol will be listed as the organizer and Jim the creator.

<source: https://support.google.com/a/answer/117596?hl=en>