As far as I know as long as you have a reservation there is no time limit as the first day is paid regardless. If you are asking by when you have to cancel so as not to be charged it's usually by 6pm day of or 8pm for Redicard members.
After midday as far as I know
It is your room until 11:59 PM the date you booked it for
I agree with Sheila.
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