The reboot probe is a timed probe, which means you schedule it in the controller to start at time(s) you want a reboot to happen. Unfortunately the controller timespec is not advanced enough for this type of usage, so the reboot probe itself has additional logic to determine if it is time to initiate a reboot once it it started.
This means that you schedule the probe to start at the normal reboot time (eg. 2 am each night) and you configure the /timespec/activate_when key to decide which days you want the reboot to happen (eg. active_when = 1st tue of month or 3rd tue of month).
You can add a -test argument to the probe definition (rightclich+edit on the probe in Infrastructure Manager) to make the probe just log when it would have initiated a reboot instead of actually doing so.
Regards, Koert