Not really an answer to your question, but I imagine you’ll find it interesting. You can push the approach push button when:1) cleared for the approach 2) the to waypoint is a final descent point (a point where you can find a coded FPA)
the change came about last year if I’m correct. PRO-NOR-SOP-18-C P 8/28
You're supposed to do a managed descent to the first final descent point altitude and then, when the FDP is the to waypoint, push approach P/b to get final app.