iwc AQUATIMER CHRONOGRAPH Mode D'emploi page 28

Time setting
Pull out the crown to position 2. This will stop the move-
ment. To set the time accurately to the second, it is best to
stop the movement as the seconds hand passes 60. Now
move the minute hand a few minute strokes beyond the
time to be set. Then position the minute hand by moving it
gently backwards until it is exactly above the correct
minute stroke. This ensures that the minute hand begins
to move immediately when you restart the movement. To
start the seconds hand, push in the crown to position 0.
When setting the time, please be aware of the date
change, which always takes place at 12 midnight. If this
change has already taken place at 12 noon, you must
move the hands forwards by 12 hours.
Important: Although the watch is water-resistant in pos-
itions 0, 1 and 2, the crown should always be screwed in
again for normal use (position X).