Restrict access to forum based on post count

[cheekymonk3y]

Hiya, I want to restrict access to certain forums based on member post count. I am aware I could do this with promotions and usergroups, but, I don't want to do that because (I Think) promotions are based hourly, and the promotion and access to the forums will not happen exactly when they reach a certain amount of posts (I think). Maybe I am wrong about that, in which case, could someone pls tell me.