DD-MM-YYYY, it's perfectly OK

Just because you're writing in English doesn't mean you ought to adopt the date format practised in the US as such. This habit is pretty common among Indonesian learners of English who assume that the 'date-month-year' format (e.g. 11 August 2013, 11-8-2013) is used in Indonesia, whereas the 'month-date-year' format (e.g. August 11, 2013, 8-11-2013) belongs to the US, hence English. Can I say something here please? The US isn't the only country speaking English as a native language--ever heard of the UK, Australia, and New Zealand? So why must the (American) English usage override the others?

And for your information, DD-MM-YYYY is widely adopted in the world, much more prevalent than MM-DD-YYYY in fact. According to Wikipedia (as of 11 August 2013), the only countries adopting the latter format are the US (exclusively), Canada, the Philippines, and Saudi Arabia. So, you aren't alone, fellow Indonesians; you're in the same club with European, Latin American, and North African countries, among others.

And personally, I think DD-MM-YYYY is nicer because we sort the calendar date from the smallest unit (day) to the biggest (year). Using the same logic, YYYY-MM-DD is also useful particularly when we want to sort a number of computer files whose names are replaced by dates. But MM-DD-YYYY doesn't demonstrate that sequential property, unless we belittle the importance of the year.

Below are posters of two concerts in Jakarta using MM-DD-YYYY. But note that DD-MM-YYYY is also common among them.