IWC Schaffhausen Da Vinci Mode D'emploi page 21

Setting the perpetual calendar
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Pull out the crown to position 1. In this position, you can use the rapid
advance function to move the calendar forwards incrementally by rotating
the crown slowly in the clockwise direction. The calendar must not be
adjusted between 8 p.m. and 2 a.m.
The leap year display has the 4 positions «1», «2», «3» and «L». «L» stands
for «leap year». If the current year is a leap year (i.e. the year is divisible by 4,
e.g. 2012, 2016, etc.), you must adjust the calendar so that the leap year
display shows «L». «1» corresponds to the first year after a leap year, «2» to
the second and «3» to the third. Once set correctly, the perpetual calendar
will automatically show the correct date at all times. You need do nothing
until 1 March 2100, when you must manually move the calendar forwards
by one day because, although 2100 is divisible by 4, it is not a leap year
according to the Gregorian calendar.
Please note:
You must not move the calendar forwards beyond the correct date. The
complicated movement is mechanically pre-programmed and cannot be
reset without accessing the mechanism. Nevertheless, if you have moved
the date forwards beyond the correct date, you have two options:
You can either pull out the crown to position 2 to stop the movement until
the calendar setting once again matches the correct date. This makes sense
if the setting is only a few days ahead. Alternatively, slowly advance the
calendar four years until the correct date is reached. Another possibility is to
take the watch to your watchmaker, who will be able to reset the calendar
by accessing the movement. This makes sense for larger adjustments.