FAA Foreign Operations Specifications C060f state:
Operating Limitations: The foreign air carrier shall not begin the final approach segment of a CAT3 instrument approach procedure, unless the latest reported controlling RVR for the landing runway is at or above the minimums authorized for the operation being conducted and all of the following conditions are met:...
According to US definition the final approach segment starts at the OM or equivalent position.
Furthermore (CRAR United States):
Activation of LVO is normally neither announced on ATIS nor reported by ATC. At some major APs this may be handled differently. ATC my INFO only about actual VIS or if AVBL the RVR once with the approach clearance and again with the landing clearance given by TWR controller. Determination that existing WX/VIS is adequate for APCH/LDG and TKOF is the responsibility of the pilot.
Honestly - flying LOVIS Ops in the United States appears to be far more complicated than in other parts of the world (I am quite sure 411A will disagree on that
). Far too many rules and exceptions to be found in the regulations.
My two cents...