At night, impossible to see the markings and read the aiming point from them, sure pilots need to pick up the 'collision' point by obesrving the visual field expand.
About 500 is the first feeling I get for it, the centreline lamps become distinct one from another. The key is flying the GS / FDs well with a steady pitch so the outside image is stable. Around 300 it starts making sense to the brain, not earlier than that to me. If no GS until that point, PAPI + V/S are the tools, Mk II eyeball + V/S and a little gut when below.