This is true And you'll have to go thru a drive cycle once the light goes off, to get the ready status. Just because the light goes off doesn't mean you'll pass, if the system is not ready, it'll still fail.
correct the GCAF states a 2 week driving prior to the next re inspection to allow this process to take place...I have seen some that takes longer then 2 weeks,some longer then 400 miles and some as short as 3 miles..... all depends on the car