Unless its changed since I did mine a few years back (I am pretty confident it hasn't) you need to hold a CPL(A) before commencing the rating, and a NVFR before the test. Theoretically you could do your FIR with 150hrs and a brand new CPL(A). The 30hrs Dual and 20hrs mutual is the hours the course must consist of.
Grade 2 you need 250hrs instructional time, of which 200hrs must be ab initio and 50hrs nav.
Grade 1 is 750hrs, I don't recall what the split is for ab initio.
Hope that helps a bit.