I'm going through the same process as you. You could be waiting a lot longer, I past 6 months of waiting last week.
I've done a lot of research and digging on mine so could help on understanding it from a new build perspective.
First does anyone in your new estate have a working line?
Sounds like all the infrastructure is in then if 75% people have lines.
Do you have a proper Openreach box thing outside your house or just cables stick out of the ground?