Since Red Hat 8 uses SystemD, the best way to delay HAAst start is with a service timer. Create the file haast.timer in the /etc/systemd/system directory with the following contents
[Unit]
Description=Delay HAAst start by 1 minute on bootup
[Timer]
OnBootSec=1min
Unit=haast.service
[Install]
WantedBy=basic.target
Then, enable the HAAst timer and disable the service:
systemctl enable haast.timer
systemctl disable haast.service
And finally, in your haast.service file change the WantedBy line to read:
[Install]
WantedBy=haast.timer
Next inform systemd of your changes:
systemctl daemon-reload
And your HAAst start will delay by 1 minute on bootup. You can adjust the delay as you need.