This is a response Openreach gave a forum member via the nga email.
"The change in dates on the website is as a result of the recent Advertising Standards Agency ruling –Openreach will be moving to provide a six-and-nine-month view of when exchanges will be enabled to improve the accuracy of this data when it is presented to end-users by CPs.
However, the deployment plan remains the same – the majority of people who were given a March date will still be able to receive service by that point, we are just unable to provide a three-month view any more as a result of the ASA ruling.
Whilst in most cases we were able to forecast an accurate date, deploying fibre is a complex engineering job which involves planning consent in some cases, power provision, traffic management, etc. Therefore there will always be the potential for unexpected delays to occur for an individual cabinet. Moving to a six-month view reduces the impact of such delays on our predictions.
Also this bit from the Openreach where and when site in the FAQ.
In order to avoid repeatedly delaying these cabinets, we have moved their due dates to the end of our commercial programme to reduce multiple changes to the likely activation date. We will continue to seek solutions for these cabinets and where possible will activate them before the end date given.
Orange BB 5856/448