OK, my sister has finally gone live with Plusnet (delays were not caused by PN, but by BT being tardy with her MAC).
Despite not being able to cite me as a referrer during the sign-up process, she was able to speak to a human being, and told I would be credited as the referrer once her connection was up and running.
So my question now is at what point should I be able to see it on my a/c? Reading the blurb about how it works, it looks as if I probably wouldn't be credited with any discount until her next billing date, which I assume is about a month from now?
But shouldn't it show as pending or something, so I can at least see the referral has been logged?