The arrival window, and why it is a window
From the moment an hour is confirmed to the knock at your door, reckon on forty to sixty minutes anywhere in central Amsterdam, day or night.
Forty to sixty minutes is the figure, and it holds across every central district, in the afternoon and in the small hours alike. It is measured from the point the booking is confirmed in the thread, not from your first message, which is why the thread is kept short.
Why a window and not a time
Because the honest answer has a range in it. She may be twelve minutes away or she may be across the water; a bridge may be up, a tram may be holding a junction, a taxi may take the long way round a closed street. A single promised minute would be a guess dressed up as a fact, and a guest sitting in a quiet room watching a clock tick past a promised minute has a worse evening than one who was told forty to sixty.
Using the window well
It is enough time to do the three things that make the hour better: turn the heating up, put one lamp on and switch the overhead off, and leave your phone face down somewhere it will not light the ceiling. It is not enough time to go out for anything, and a guest who leaves to fetch something almost always comes back to a missed knock. There is more on that quarter of an hour in the guide to a quiet booking from first message to goodbye.
Where the window does not apply
Schiphol and the airport hotels around it are their own arrangement. The journey out there is longer than the city figure and it is talked through and agreed with you before the hour is held, so you are working from a real number rather than a hopeful one. Nowhere outside Amsterdam and those airport hotels is reached at all.