In my case they connected the CAB in about March 2012 for the eventual launch at the end of June 2012. Then at the end of June the status changed to the end of September 2012. BT OpenReach website still said "Coming Soon".
Then a few days ago (16th July) the BT OpenReach website and their twitter feed announced that SEAFORD, East Sussex was "Accepting Orders".
BT OpenReach Accepting Orders
But I can't find a provider to place an order with... they all say that I can't get it apart from TalkTalk who say I'll be able to get 70mbs down and 19mbs up but I can't order it until October. I've checked my friends address who lives on the other side of Seaford and they can't get it either so it's probably not a CAB issue.
So I'm assuming it take a little while for the change in Exchange status to communicate itself to the retailers but how long does it take?