Stop Allowing joins after CB2 on coordinator

Here is my configuration - Coordinator has NJ=0 to not allow joins. I want to allow ONE router to join, so I issue a CB=2 to allow joins for 60 seconds. One router joins - great! I get the API frame 0x95 so I know that a router has joined. Now, how can I not allow any other routers to join for the rest of the 60 seconds?
Thanks for any info.

All you can do is to set NJ to 0.