Danou_71
Correct. You must have your required minimum RVR at the OM/1000' ARTE/4 miles or equivalent point. If the RVR is below your minima at this point you must go around.
If you have continued your approach because the RVR was at or above minimum at the OM/1000' ATRE and it subsequently goes below minimum then you can continue the approach down to DH' and land IF you have the required visual reference.
A4