The options should be active immediately. If you set the 'force action after' to 120 and the 'countdown time-out' to 120 then the option will be greyed out. It means the timeout is already at the max number.
Could you supply a screenshot of the reboot setting from the Deployment Template. (I may be reading this incorrectly)
You're right. I had the force action AND extend time both to 120 mins. Once I set the force action time to 240 it was active.