I am looking to construct an A/B test with Journey Builder in order to test sending our first welcome message at varying times. Right now it goes out immediately. Ideally, I am looking to use STO "optimal send time" to see if it improves open rates.  

Where I need help is in understanding how to remove certain subscribers who are in the step queued for an optimal send time.  For example, subscriber A has a status change in CRM while waiting for the optimal send time, and we do not want to send an email to the subscriber anymore.

As a side note, I'm not planning to use the predictive side of STO for this test because a vast majority of these subscribers have never received an email from us.  

Thank you for your help.   

#MCAskAnExpert#send time optimization