The arrival window is the forty to sixty minutes between the office confirming and her knock, the same span for every central Amsterdam address at any hour.
Once the thread says yes, a clock starts. Forty to sixty minutes later, she knocks. That span is the arrival window, and it is the timing promise behind every booking wanted tonight.
The window does not shrink for a hotel beside Dam Square or stretch for a flat out beyond the Amstel. It is quoted as one range for anywhere central, because the roster of forty-five lives across Amsterdam rather than waiting in a single building, and whoever is matched to you sets out from wherever she happens to be. A figure promised street by street would only be a guess wearing a uniform.
Amsterdam nights are uneven. A bridge lifts, a canal street is blocked by a late delivery, the crowd in the old quarter slows a taxi to walking pace until the bars empty. Forty to sixty minutes absorbs all of that, so nobody has to send a message about a five-minute delay.
Many people spend it the same way: a shower, the lamps turned low, the balance counted out or a card left within reach, the phone face down on the table. If the building has a gate code, a night porter or a lift that needs a key, send those details while she is on her way rather than once she is standing outside.
Schiphol and the airport hotels run to an hour agreed in the thread instead. A booking made for a later date arrives at the start time you named rather than on the window. On a booking that carries a deposit, she sets out once it has cleared, so settling it promptly keeps the wait inside the range. For a booking wanted within the hour, the tonight guide walks through the sequence.