From Experience of a Openreach FTTP delivery.
Tuesday 12th September, Openreach staff tipped up , commenced opening the footway junction boxes and commenced installing draw cords from each house to said footway boxes. Houses in my road are all underground duct fed.
Subsequently they installed multiway manifolds for connectorised delivery in the footway boxes. Then connected them all up to an aggregation node some 500 metres away. Disapeared leaving it all connected up I believe.
Eventually came back did testing of "light" available in each of the manifold ports. Within 5 days of this testing the BT Wholesale/ BT ADSL Checker etal went WBC FTTP Upto 330Mbps / Upto 30Mbps
This availability date was Thursday 9th November.
This "service available" delivery took circa 8 weeks some 32 working days; and during this time included some duct cleaning too.
So if they started yesterday it will be rather tight for Christmas......don't forget post being available there's the 4 to 6 week delay in installing the bit of fibre that enters the house, installing the ONT & BBU etc.
If the Openreach team are under time constraints to deliver by Christmas then no doubt they will deliver a "service available".
Best of luck and in answer to your initial question is; first "how deep are your pockets?"
I suggest you need to trawl at least 5 suppliers to get an idea of what they can deliver, what their service level agreement is, what if any download limits they impose and finally how many beer coupons a month they will want from you
You'll most likey end up doing some spreadsheet bashing to find how much extra this FTTP will cost.
You should some "fun" with that no doubt. (I did).