The RTC handles Leap year but does not handle the Daylight Savings.
DATE[1] is the year, DATE[2] is the month and DATE[3] is the day. DATE[4] is the day of the week.
Leap year is the year that is divisible by 4. So year 2004 is a leap year but not 2005, 2006 and 2007. That should give you a clue on how to handle the leap year.
12 days and 4 hours = 292 hours = 17520 minutes. You may want to construct a timer that will increment a counter every minutes and when it counted down from 17520 to zero it can trigger your event - I think it will execute a lot faster and the code is cleaner too.