I expect if you look using this checker
that will also have 30 June. The people talking to you are probably looking at the same database, though perhaps through a different checker.
Quarter-end dates like that I'm afraid mean nothing more than the cabinet is still scheduled. They always have done. They are very likely to slip by one or more quarters within the last fortnight of the date shown. It seems to be a complete quarterly review.
It's still possible they could reach it for your cabinet, but as MrSaffron says, a lot of non-Openreach resources need co-ordinating and it only needs one step to encounter a problem and the whole plan gets delayed. The Openreach resources moving immediately to the next job and re-scheduled to this one when the problem is cleared. But that re-scheduling tends/seems to be to the end of their schedule at that time, not to the top.
I expect you can rely on it being before that January 2018 date, but that does look to be the planned timespan, with the job currently either still pending or maybe already waiting for the late June review.
Not long before going live a "real" date may appear in the checker I gave above. Then 2-3 days before it that date can disappear completely with no replacement. That nearly always means it is technically live but just waiting for the database of live ones to be updated. (I'm surmising there are at least two databases involved, as the way things happen strongly suggests it).
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