This delay between an email account being create and being listed can cause organisational issue, like a users being unable to find the email address for a new staff member.
To resolve this you have two option, manually update the Address Book or customize the update schedule.
This document explains the process of how an individual can get their information updated in GAL.
If their information has already been submitted, this explains how to manually download their address book to force their Outlook to updated its information.1.
To get the OAM to immediately generate run the following command: Update-Offline Addressbook “name of offline address book”.