NTP comes with a script, ntp-wait, that is specifically designed to be used during the boot-sequence for the purpose of waiting until the clock is sync'd before starting time-sensitive applications.
See http://support.ntp.org/bin/view/Support/StartingNTP4 for more information. BCP is: - Start ntpd as early as possible during the boot sequence - As late as possible during the boot sequence run ntp-wait, before starting things like Dovecot and database servers H
