What happens in a Wait Until +/-= Days campaign and the Date field changes?

[Anonymous]

I'm building campaigns using the new Wait Until (+/-) days feature from the March Release, and have a question on a possible use case.

Let me set up the situation first:

Current Subscriber (binary field) 
Expiration Date is 01/01/2014 (date field)

I set up a triggered campaign

Smart List Trigger:
Data Value Changes:  Field is "Current Subscriber"   New Value is "N"

Flow:
Step 1: Wait:
Advanced Wait Properties - Type of "Date Token"
End on "{{lead.Expiration Date}}"  "Plus" "90 days"
Use Next Anniversary is UNCHECKED

Step 2: Send Email: (my "have you missed us" renewal  email) 

Schedule:  Activated.

This should send my message 90 days after their expire date, triggerd by the Current Subscriber field changing to N.

First question is a basic confirmation of the logic of the flow:
Changes to N on December 15th 2013?  Email is sent on April 1, 2014,  which is 90 Days after 01/01/2014
Changes to N on January 15th 2014?  Email is sent on April 1, 2014, again, because it is 90 days after 01/01/2014 
Changes to N on April 2, 2014?  Email is sent immedeately, because it is already more than 90 Days after 01/01/2014  

Second Question--what if the expiration date changes after the campaign has been triggered?  
Status Changes to N on Decmber 15 2013 which triggers my email to go out on 4/1/2014.  
However, before 4/1/2014, the Expiration Date changes to 06/01/2014.  

Does this email still go out on 4/1/2014 because its delivery was already triggered?
Does it get cancelled because the date changed?
Does it get moved to August 30th (90 days after the new Expiration Date)?

[Anonymous]

Steve, based on other Marketo logic I've observed, my bet is that the wait will be based on the original date, you can easily test this with a more recent date and a shorter wait time. 

You could add a choice to your Send Email flow action that would check that the expiration date was 90 days prior and if not, the action would be "Do Nothing".  You can also trigger a smart campaign based on the change of expiration date, so you can set up another email when this occurs. 

[Anonymous]

I've had several conversations with support about this and my understanding is that he moment a lead enters a Wait step, the wait time is set and cannot be changed. In addition, whichever step number the Wait is, the next step the lead will go through is <insert the Wait step's number at the time the lead entered it> + 1. So for example...

Let's say a lead enters a "Wait 2 days" step and that Wait step is step number 4 in the flow. The lead will wait 2 days (even if you change the value to 3 days before those 2 days are up), and then it will move into whatever step number five is at the end of those two days. So if during those 2 days you add a new step at the beginning of the flow (which would in turn make that 2-day Wait step become step number 5), then the lead would end up going through that Wait step twice because it has waited 2 days and then moved into step number five, as explained in the second sentence of this paragraph.

The flow would work normally for any leads who go through the flow after you've made those changes.