I did not know that, but it is not really for reasons of age of the concept that I would prefer not to wear one. It is more that I am not from that district, but I am from my family, if you take my meaning. If I were told with some certainty that between period X and Y folks in the area my ancestors occupied wore a certain district tartan, and that this predated the acceptance of what is now the clan tartan, I would certainly consider it, but I am aware of no such evidence.
I'm betting, too, that the entire history of tartans in not so cut and dry that any one family or district tartan can really be said to be older than any other. It may be possible to nail down dates and times that certain tartans were worn by certain people in certain places, but from everything I've read on here so far the early history seems quite convoluted. Of course, you are likely to know more than I do!
This whole thing is just fascinating, really, and I did not think (though I might have, had I considered it!), that it would be so complicated as it is!