Hmm, as a Dutch person I don't like this phrase. I would never say that and would find it a little awkward if someone said it to me. If you want to blend in with the Dutch, leave out the 'next' and just say "tot woensdag!" If you want to stress the fact that you're not meeting this coming Wednesday but the next after that, use "tot volgende week woensdag" (See you next week on Wednesday)
It's a common phrase in the films of director John Landis. Before then, it was a line in 2001: a Space Odyssey.
It's very informal (and also very uncommon in American English), but it's technically correct.
I'm sorry to say that's not accurate. Here are a couple of explanations (it's interesting to note that 'till' as been around even longer than 'until', so the former couldn't possibly be a shortened form of the latter): http://grammarist.com/usage/until-till-til/ http://www.quickanddirtytips.com/education/grammar/until-till-and-til
As many native English speakers are still confused about this, I won't blame you, but I want to provide learners--as well as native speakers--with the proper usage and history of these words.