Sadly this is all quite normal as BT's dates are only rough estimates and tend to shift both backwards and sometimes forwards in time. In other cases some upgrades have been suspended / cancelled completely until other problems can be resolved first and we've seen a few put back by an entire year.
BT occasionally mentions these changes specifically but most of the time they happen quietly in the background via a tiny database change. The lesson is, don't allow your expectations to get ahead of reality. Deploying FTTC / FTTP is quite tricky and requires some major work so it's to be expected that many locations will suffer delays.
Delays like this are practically normal for most ISP / telecoms firms when rolling out new tech.
Mark 'Winter' Jackson
Editor-in-Chief - ISPreview.co.uk