VM should credit your account, with any auto comp due, within 30 days of activation (which you say is today, if 'fitted' means you are up and running with VM).
It is the subject of routine and regular topics on here where VM tries to dodge paying auto comp.
The OFCOM doc refers to 'the date initially confirmed in writing' when the supplier said it would 'activate a customer’s fixed line or broadband service'.
VM has chosen to muddy the waters with the idea of a 'provisional' installation date and the fact that it often gives a date for the cable to be installed and a later date for equipment to be installed.
VM's written info usually refers to a 'technician visiting to install kit' which would be the activation date from which auto comp is due as per
https://community.virginmedia.com/t5/Networking-and-WiFi/Ofcom-compensation-on-installs/td-p/5416574
Sometimes two dates are given (one for the cable installation and one for the technician visit) as per
https://community.virginmedia.com/t5/Forum-Archive/Install-date-date-can-I-have-an-honest-answer/m-p...
The activation date is the later date for the technician visit.
In topics where VM tries to claim a 'provisional' installation date the customer might see something like this which mentions extra outside work may be needed
https://community.virginmedia.com/t5/Forum-Archive/Technician-No-show/td-p/5396742
Mostly the ombudsman has thrown out claims of provisional installation dates but much depends on what the customer is told along the way and what evidence the customer has kept as proof.
