I'm still writing '09

How long should it take before you automatically write the new year at the end of a date?  We're two weeks into the new year, I have to write the date a number of times a day almost every single day of the week and still I'm writing '09 or 2009.

I had the same problem when I got married (all those many years ago).  I'd practised my new signature over and over again, making sure that there wasn't too much of a "flourish", yet on the first occasion I had to sign something I signed it with my maiden name.

Is this a mental block?  Are you having the same problem?  I think it's going to be another week or so before it finally sinks in.

Photo from "Optical Illusion" on Flickr