Having spent 31 years doing, among other things, the Final Director at Heathrow I never heard of that one. I don't know of any Heathrow controllers who employ that method, but there are plenty who can sit there for an hour and get inch-perfect spacing (not me, I hasten to add)!
Just looked at your formula - asuming 180 kts groundspeed you're suggesting a turn-on starting at 1.8 miles from the centreline. I don't think that would work! If you double the distance you might get close.