If your area uses the
https://one.network/ you can look on there for roadwork permits, it's free to register and then you can select a time period of more than two weeks, look for telephone works mentioning fibre, pon, or fibre cities as an indication. If your area is not showing anything then the council may have a site.
Our area Ramsgate and Broadstairs appeared on the Fibre list around the start of the year, they surveyed our estates ducts in February, but no installation has yet been done, although a very small bit of Broadstairs is live. They have mainly started in Ramsgate first, and are working their way across, see
https://labs.thinkbroadband.com/local/broadband-map#...
So in answer as to how long, it could be very quick depending on how much work they've already done or it could be very long. If your supplied overhead by poles then it may be quicker, or if your on a recently new estate with good ducts it could be quicker, our estate was built in the seventies and there are no ducts from the street to the houses, mine is direct in ground so I think they will do the easier areas first.
As they are already laying fibre it will most likely be sooner rather than later, but the top of my brothers road went live weeks ago but he's still not live, even though they've worked on his telephone pole some time ago.