For us, from registering an interest (the day we moved in) to the installation was around 4.5-5 years.
Not sure about how it all works regarding capacity/cost, the green box isn't far away and from what I saw there were conduits from the end of our road to the green box already for the surrounding houses.
They only had to channel about 50m to provide access to potentially 5 new customers.
Unfortunately, the access was presented to the wrong side of the houses, the caps are on the left, and access to where all the other services enter the house is on the right. I did mention it to the guys digging the road very optimistically as I knew at that point they wouldn't be able to just change the position.
When we had our installation they used the neighbouring access cap to avoid having to dig up the length of our driveway and then cable around the house.
Unfortunately, the bit where the engineer said "We won't cross the corner of their garden, we can bring it in through yours" turned out to be a white lie, after the soil settled we saw our green conduit appear in their flower beds. Luckily we're on good terms with them and they've not complained, but if they ever move I'd be concerned about new neighbours accidentally putting a spade through it.
Sorry, I guess my point is if you are a fresh install keep an eye on things as it's easy to not get things right.
