I have no idea where the 6 months comes from ?? The 'mark-ups' would have washed away well before that time period elapsed.
What I have laid out above, is the bog-standard template. Unless 'you' are involved in the actual build programme, 'you' will not know what is going on behind the scenes especially where civils is concerned. Take chakobsa's 2 x new poles that he mentions ..... the T1 contractor does all the running by applying for permits with the HA and doing all the necessary searches for exisiting services in the vicinity.
There may be HPP/MPP gas pipelines in the area and they have to involve Cadent, who are notoriously slow to respond, so this could easily take the 10-week glide path beyond its ECD .... but 6 months ??!! No, nay, never. OR would be kicking butt.
Like I have said though, I am nor part of the build programme so have no idea of timescales/issues/challenges in that locality. Every single PON build is bespoke.