See LASORS Section H - pre-requisite flight and theoretical requirements.
Before starting a FI course a PPL holder must have 200 hours total flight time of which 150 must be P1. (The 200 hours must include specific numbers of hours of certain types of flying.)
It follows that if a PPL holder needs 200 hours before he or she can start a FI course, the minimum number of hours a PPL holder needs to have before he or she can instruct on a PPL is 200 plus the number of hours taken to get through the course and pass the test!
Happy flying!