I always cooked them straight away without any problem, but maybe I was lucky. Be sure, though, to dust them with flour, so they won't stick while you put them in the boiling water. I generally use rice flour for dusting my freshly made pasta. I don't know whether it's true or not, but in my opinion it does a better job in preventing stickiness, even if you plan to consume them at a later time.
As a final note if you can't hang your pasta you can still dry it a bit by lying your fettuccine in a wooden board for a while, and keeping the board in a dry place.