Kitchens here serve late, and a table booked at an hour that would be closing time elsewhere is entirely normal. If 11:42 pm is when you are expected, the countdown gives the exact wait rather than the guess that has everyone standing outside twenty minutes early or arriving fifteen minutes after the rest.
There is nothing to start and nothing to choose. The page reads the clock on your device, works out the gap to 11:42 pm, and redraws it every second for as long as it is open. Leave it in a background tab if you like; the number will be current whenever you look back at it.
Twelve o'clock is where the 12-hour clock is weakest: 12 am and 12 pm are read the wrong way round often enough to cause real trouble with bookings and deadlines. Writing the same moment as 23:42 removes the problem entirely, because a 24-hour figure only ever points at one instant in the day.
Common questions
What happens once 11:42 pm has passed for today?
The count rolls over and carries on towards the same time tomorrow. That happens on its own at the moment the time passes — the page does not need reloading and there is nothing to reset by hand.
Which clock does the countdown use?
Your own. It reads the local time and time zone from the device in front of you, which in the Emirates means Gulf Standard Time, UTC+4. Travel and the count follows whatever the device picks up.
Will it alert me when 11:42 pm arrives?
No. This is a live figure rather than an alarm — nothing sounds, vibrates or notifies at zero. If you need interrupting at 11:42 pm, set an alarm alongside it and use this page as the running total.
Do the clocks change here?
No. The UAE has no daylight saving at all, so the offset stays at UTC+4 in every month. When the gap to Europe or North America shifts, it is their clocks that moved, not yours.