Suggestions.
+ Configuration Window
+ Contact Specific (Enable for Specific Contacts Option)
+ Use Seconds for Setting the Timer
Also, does the script start the timer from when you last say something? ... say its set to nudge after 10 minutes if theres no responce from the Contact to your Message Sent 10 Min ago? I would guess it works this way.
Edit
I just noticed your original post, you are already on top of some things I mentioned.