the elessar

[Galin]

Also, "Olórin" would likely have been known to Galadriel from her time in Valinor.

To me the passage from The Silmarillion suggests that perhaps Olórin did not make himself known, in general anyway, as Olórin at least. But that said, he does appear to have been known to Glorfindel in Aman. And after Tolkien notes that Glorfindel had become a friend and follower of Olórin in Valinor, JRRT adds:

'That Olórin, as was possible for one of the Maiar, had already visited Middle-earth and had become acquainted not only with the Sindarin Elves and others deeper in Middle-earth, but also with Men, is likely, but nothing is [> has yet been] said of this.'

JRRT, Last Writings, Glorfindel II, The Peoples Of Middle-Earth

So, I'm thinking that Tolkien was possibly thinking that Olórin visited Galadriel here, before the Third Age...

... otherwise, I'm back to [if this is Gandalf the Istar and thus well into the Third Age]: why would Galadriel consider employing the Elessar stone when she can already use Nenya? Not that we can't think of a reason, perhaps, but so far it seems easier [for me] to think Tolkien imagined an earlier visit with the stone.