that is absolutely possible. Did you notice, that if you add the automatic action "Add Reminder" you always have to define the "Send Date"? That is your advantage. Usually there is the simple calculation that returns the Value = DateTime.UtcNow. But that can be amended. For example:
import System static def GetAttributeValue(Reminder): CurrentTime = DateTime.UtcNow Value = CurrentTime.AddMinutes(30) return Value
That will allow you to set the send date to 30 minutes into the future. The mail engine will consider the send date before sending, so you will be able to use three subsequent "Add Reminder" actions and every one of the actions will have a different send date. Just set a different value for the AddMinutes method in the different "Add Reminder" actions.