Hello @JohnAlaric,
The delay in alerting likely comes from Core waiting to send an alert until a hard state change occurs. What that means is that when a host or service first enters a non-OK state, it is in a soft state. It does not enter a hard state until the max_check_attempts limit has been reached. Once that limit has been reached and the host or service enters a hard state, Nagios Core sends an alert out. It waits so that false positives are limited and needless alerts are not sent.
To limit this delay, you can lower max_check_attempts so that the host / service enters a hard state faster.
For more information, I recommend reading the documentation on Notifications and on State Types.
Let me know if you have any other questions.
- Emmett