It only says
"Applicants shall only take the examination when recommended by the approved training organisation (ATO) responsible for their training, once they have completed the appropriate elements of the training course of theoretical knowledge instruction to a satisfactory standard."
That appears to give the ATO authority to say when the student is ready to take an exam. I suppose that might mean after they provide x hours of groundschool but it might also mean as soon as they think the stude is ready on the basis of his/her own study plus whatever pearls of wisdom their instructor imparts during training. I rather think most schools do the latter? Mine certainly did in 2003-5, unless things have changed.