Gandalf....fortune teller??

[Inziladun]

Interesting topic!

I'd think your first option the most likely, based on a few quotes.

After Bilbo's departure, but before Gandalf knew his ring was the One, G. tells Frodo:

'But if you take my advice you will use it very seldom, if at all.

So, he didn't expressly forbid Frodo from wearing the Ring, at least in the manner Bilbo had: to escape from nosy or annoying neighbors.

Later, at Bombadil's house, when Frodo wears it:

Frodo was delighted (in a way): it was his own ring all right, for Merry was staring blankly at his chair, and obviously could not see him.

I don't read there a sense that that was the first time Frodo had used the Ring.

And in Lothlórien, much later, Galadriel tells Frodo:

'Only thrice have you set the Ring upon your finger since you knew what you possessed.'

Meaning, after Gandalf's talk in The Shadow of the Past, because it adds up: Frodo used the Ring at Bombadil's, on Weathertop, and at the Ford of Bruinen.