Check your theatre guide
The purpose of this response is to point out that some countries requirements for beginning an approach are different than others. Jepp lists these in the theatre guide...chapter 11. I realize the original poster has ATH as the g-ref. Many on this forum will be from other hemispheres.
Brazil
Approach Ban
The final approach segment of any instrument approach procedure shall not be initiated, unless the controlling ceiling and controlling RVR, or if no RVR is
available, the visibility conditions are reported to be at or above the minimum
authorized for the approach being conducted.
NOTE: 5 Octas or greater (Broken or Overcast) constitutes a ceiling.