I cant say directly about BT Infinity 2; but I ordered an upgrade back on 18th May from EE, from ADSL2+ to 40/10, FTTC having been recently installed and activated in the area.
The Bright Box 2 arrived 3 days after placing the order. Nothing about its installation requirements, other than typical "Plug it in".
My NTE is almost an ancient on; and I expected to have an engineer appointment etc.
The installation date of (by?) 5th June was included, though not clear exactly what this meant.
Was it that the installation would be some time in the period up to 5th June; or was it scheduled for that date?
In the meantime, I had organise fish wires to pull through new wiring, if needed etc.
On 4th June I phoned the EE Help Line; and fortunately got a "Customer Adviser" who clearly knew what he was talking about.
He informed me that unless something prove to be faulty, there was no need for an appointment.
On the 5th June, approaching "High Noon", I spotted a KELLY van across the road, at the PC, with two lads at the PCP.
Just as I was speaking to one, a trainee, the other happened to be confirming which line he was working on by ringing 17070 - and I heard my own phone number being read back.
Returned home; and some minutes later plugged in the BB 2.
It took about 3 minutes to set itself up; and has been working since.
It is running at around 36 Mbps Down, 9.5 Mbps UP, on a line which is now about 300 Metres long.
In the house, the line supplying trhe Router is rough phone wiring from the NTE up through the stairs, across a landing underneath the carpet, to a socket just inside the "office", where a conventional "Phone Extension Cord" completes the line to the BB 2.
There are are another two extension wires off that "office" socket, one actually being used.
Absolutely no changes to the existing higgledy-piggledy internal wiring, apart from fitting the two supplied VDSL Splitters, one on the BB 2 Router extension, the other on a Cordless Phone Base Station, elsewhere.
Possibly someone who has done a similar upgrade to you may respond with their experiences.