This is tuning the job / result / alert ... I don't have an answer for you ... you need to test and iterate...
You can also take a look at this for tuning what is considered and alert.
I will say In General... Machine Learning + Alerts is not generally a great fit for "Race the Clock" alerting... if you are looking to be alerted within say 1-5 mins and ML job is probably not the right approach / great fit.