There is a site setting called notify about queued posts after that sets the number of hours to wait before sending a notification to all site moderators about posts in the approval queue. The setting defaults to 24 hours. You can set it as low as 1 hour. Setting it to 0 will disable notifications about queued posts.
Notifications about queued posts are only sent to moderators, they are not sent to admins. If you’re an admin and wish to receive notifications about queued posts, you will need to grant yourself moderator status.