I got a letter some months before the due date when I was 60, saying that if I wanted to claim, I had to let them know. I'm still working so not claiming it yet (and it accrues a % for every year I leave it) - all I have to do is let them know when I want to start receiving it.
This site is really useful, it has all the info you need - it says she will be contacted 4 months before she might start receiving it.
http://www.direct.gov...tatePension/DG_183111
so as you say - any time now!