Night entry covers everything between the street and your door after hours: locked street doors, keycard lifts, entry codes and night entrances, all of which belong in the first message.
A booking at eleven in the evening and the same booking at three in the morning differ in exactly one practical respect, and it is not the massage. It is the building. Doors that stand open all day lock at some point in the evening, lifts start asking for a card, and a main entrance quietly becomes a side one.
Most buildings in this city fall into one of four groups after hours. A street door on a code, where the code has to reach the thread before she arrives. A lift that refuses to move without a card held against a reader, which puts you in the lobby rather than upstairs. A night entrance around the side, where the day entrance is locked and unmarked. And a reception staffed overnight, where nothing is required of you at all beyond being reachable by phone. Which of the four applies belongs in the first message, alongside the hour and the length, as the booking page sets out.
Put it in the first message rather than answering it later. A line is enough: the door code, the fact that the lift needs a card, the name of the side street the night entrance is on. It costs you ten seconds while you are typing anyway and it removes the single most common cause of a late arrival, which is a therapist standing on a pavement at half past two with no way in and a phone ringing out upstairs.
Send the door code and the floor when you book. Send the room or apartment number once the booking is confirmed, in the same thread, which keeps the most specific detail out of the earliest message. Nothing about this is unusual and nobody at any building is asked anything on your behalf.
The arrival window is forty to sixty minutes and the last two of those minutes usually need you. A phone face down under a pillow at three in the morning turns a solved entry into an unsolved one. The journal note on door codes works through the cases in more detail.
Two lines settle it: where the room is, and what time you want someone at the door. The answer comes back with a name, an arrival window and the whole figure, whatever the clock says.