Little Details

When did mm/dd/yy (or dd/mm/yy, it doesn't matter) format for writing dates first go into common use? I've tried Google, but have had little luck.

What I really need to know is whether or not that format would have been in use in Europe by the early 1900s. I'd like to be able to use the dd/mm/yy format on a bit of paper dated 1908, thereby leading to misinterpretation by a contemporary American reader who's looking at a European formatted date and gets the months and days reversed.

(Cross-posting to http://www.livejournal.com/community/hp_britglish/)

OK, I'm developing a character for a HP AU, and what he needs right now (apart for therapy for his [rather badly handled] PTSD/panic disorder/agoraphobia, whatever a professional would call it) is a prescription for anti-depressants with a side order of tranquillisers -- 'right now' being in the mid-eighties. The problem is that he was using tranx about four years ago in London, going through them so fast that his doctor began to suspect addiction and finally refused to prescribe more pills for him. Well, since then he's been on the dole, moved to another county, got a job he's overqualified for, finally and slowly started to piece his life together, and wham! he has another panic attack and realises that he's not as "over it" as he thought he was.

The snag is, I don't know if it'd be correct procedure for a British GP to prescribe these kinds of medicines for someone the GP has barely seen before. My favourite sites haven't helped much, I'm sorry to say. I suppose my character would be more likely to be referred to a psychiatrist first.