You may observe that pacemaker starts before the system time is synchronized. If you absolutely need pacemaker to only come up after the time is synced, see below.
The pacemaker systemd unit file ships with below included (LINBIT built packages).
# Time syncs can make the clock jump backward, which messes with logging
# and failure timestamps, so wait until it's done.
However, you can clearly observe that pacemaker will start before the time is synced to a remote NTP server. If you truly need it to wait until the time is synchronized you can run the below command to ensure this is enforced.
systemctl enable chrony-wait
Please note that this is disabled by default because waiting indefinitely on something that is dependent upon connecting to a remote system, might not be the best idea. Additionally it is possible that enabling this will affect other systemd services.
Edited on 2020/11/09
Reviewed on 2020/11/24 DGT