Usually you are forced to conform to the date format used by the particular site on which the program is located.
You are asked to plug your DOB into one of those interfaces where you have drop down menus to select/dial the numerals, instead of entering them yourself manually.
So there should not be any confusion about the date format being used by the site or program, as it will be clearly indicated on the program's interface.
When getting a live reading if asked, give your date of birth as April 21st 1962.
Then there should not be any confusion about that either.
BTW in Australia we basically use the European format, but often omit the leading zeroes, and only give the last two digits of the year concerned.
So today Friday June 20th, 2014 becomes 20/6/14, instead of 20/06/2014