So for it to work, you need to issue a statement every month that says you haven't been issued a NSL, and then simply not issue a statement the month you finally were issued a NSL. That would then require the government to actually compel speech (compel you to post a new notice saying you didn't receive a canary).
Of course, the above should make it blatantly obvious how absolutely absurd the blanket gag order on NSLs are.