Some areas have more information available, so useful to know, but on the theory
The BT Wholesale checker generally gives no clue about a cabinet going live until it has gone live, some of the old commercial cabinets have ETA dates but not many left like that now. The County projects should be the best information source.
So the Openreach site saying you are in the plans is good news, but would I buy a house in the area based on that - no, since plans can change and it might mean by Jan 2016 or December 2017. Time to get excited is when you see a fibre twin appear alongside your current cabinet, and even then it can still be months away.