In my experience, from identifying an area (usually 120 dwellings or less per PON), to being ready to 'customer ready' .... takes around 2 months.
Most of the work you won't see (such as the planning stages), but once you start to see the guys on-site 'Test rodding' between work-points to identify free ducts, or whether civils are required, the process will generally take 3-4 weeks.
Well the original announcement at the end of July was "starting in the next three months".
Three months had already passed BEFORE they updated the map to say "starting in the next three months".
Now granted they aren't the best at keeping things up-to-date, but it certainly doesn't appear like they started yet. There is nothing on one.network to suggest any roadworks, although presumably that won't happen until they have done extensive rodding to determine which areas need blockages clearing, etc.
To be fair, if this all lines up with being ready just after the new pricing tiers come in, that could be pretty sweet. Although I'm about 2KM from the exchange, so not sure if/how that impacts the time scale. I'm certainly not the furthest away, I believe my exchange is the largest in Sheffield, presumably why it was chosen.