Inserting compile date/time into the code in XC8
From the XC8 C Compiler Users Guide, page 229:-

5.14.3 Predefined Macros

__DATE__ to indicate the current date eg. May 21, 2004 
__TIME__ to indicate the current time eg. 08:06:31


You can parse these strings to get numbers compatible with your rtc, but what's the point of a real time clock that doesn't have the real time? 

Anyway, look at this Stack Overflow Question for a way to do it.