Found this article:
Asus: Don't Expect Transformer Prime TF700T Until After June | TechnoBuffalo
Now, the title says until after
June, but the article says "the company said those in the U.K. shouldn’t expect the Prime HD to hit before June at the earliest" which means that it could launch in June, but don't expect it earlier than that.
Still means that I have a few months to wait...