The dot is used as a separator, followed by space and matches the convention of pronouncing day, month and year as ordinal numbers (31. 12. 2006.).
Leading zero is rarely used, and in those cases which are considered bad practice, only with months (however it is also optional for the days) (6. 05. 2006.).
Incorrect use of colon has its fair share, mostly influenced by international time notation[citation needed].
Note that among the two words for "hour", sat is common used for 1 to 12 range and čas for 0 and 13 to 24, but there are no official rules.
However, Windows' region and language configuration for both Serbian variations (Cyrillic and Latin) omits the leading zero for hours and days and months in the date.