I am talking about end of down wind time. Blogs, your procedure seems to be different. Airbus wants you to time from abeam threshold as corrected for wind and start a level turn for finals, when you are about 90 degrees to the runway if correctly vertically positioned only then commence final descent. Purpose of timing is to place you at the same spot on ground for final turn. Basically a visual manoeuvre timing is for guidance. It has to be altered as required to remain visual and keep runway in sight.
Precisely as I said, Vilas. You can be at an MDA of 1500ft or 500ft, or have gone down to 400ft (PANs ops Cat C terrain clearance). It doesn't matter. Turn on time, corrected for wind. Use a Fix if you need a crutch. The crunch is, as you mention, keeping Visual with the threshold or "runway environment" on the latter part of Downwind. Very difficult if you want to
roll out on Final at 1.5nm/500ft ("Stable"). And you will almost certainly exceed the circling min vis on the first part of the base turn. Never see the runway then...
And Yes, you do commence final descent only when intercepting the "normal" 3° path. At 500ft, that means a level turn all the way round.