Is that the 12th of January or the 1st of December?

In the UK (and most of the world) dates are written DD/MM/YYYY. That is, day, then month, then year. The US is one of the only places I know of in the world that writes dates as MM/DD/YYYY. As a logical person, I can only give this point to the British.

When you're talking about a date, the date is the most specific part, then the month is slightly less specific, and then the year is the least specific of all. So to my mind (and the minds of most of the world) that's the logical way to present the date. Alternatively, YYYY/MM/DD is a good way, when you're talking about things like computer file names. Then when they're sorted they all end up in a proper order. But there is no situation in which putting the month first logically makes sense.

If you're American, and you just have to put the month first, please spell it out so the rest of the world understands you. If you tell me that your birthday is 12/01/1960, you'll be getting your card in January.