I think they show it pretty close to the US, last season it was very close, sometimes within 2 weeks, but of course it depends on Channel 4's schedules at the moment. It may be that they have to delay it a while until there is space for it. I'm sure Channel 4 know when it will be airing, so it might be worth e-mailing them to ask.
You all know whats happening in the new series dont you? Its no secret, I saw it in the trailers on NBC when I was over there, its Niles and Daphne's wedding! Should be good! Surely it can't all go to plan can it? It wouldnt be Frasier if it did