This is, at least, my two cents – the almighty moderators will do as they please, of course

The situation: partner is a EU citizen who spent the first 6 months in the UK as an exchange PhD student. She was enrolled in the PhD program of another European university and did an exchange period here. To be clear, the UK university did not award the PhD nor any other title – only the European university did.
Partner then spent a few months looking for work, then found one and has been in full employment ever since, i.e. for about 7 years.
In her application for permanent resident status, shall she specify that she started exercising treaty rights:
When she arrived here and was an exchange student?
When her PhD program finished and she started looking for work?
When she started working?
It should be a moot point because, regardless of which of these 3 it is, she has acquired permanent resident status since she started working about 7 years ago. However we are afraid the application might be rejected for technicalities – the press is reporting many such cases lately.
To be clear, she has never applied for any benefits from the UK. During her period as an exchange student and as a job-seeker she did not have private medical insurance and it’s not clear if she was covered by the NHS equivalent of her home country – for practical purposes we may assume she was not as she’d have no way of proving it.
Thanks!