According to Halacha ( Law), as said above they girls will be Bat Mitavah on their 12th birthday. Assuming they was born BEFORE sunset on the 30 June 2002, their Hebrew birthday is 20 Tammuz. ( if they were born after sunset it is 21 Tammuz) In 2014 the 20 Tammuz is July 18.
All that being said, as asked above, you don't say what you plan on doing and most things will not have someone verifying if they are or are not Bat Mizvah. BTW they become Bat Mitzvah at the appropriate age---even if you do nothing.
is the one I use to figure out days--in case you want to check out some other dates.
Edited: 8:56 am, April 08, 2013