Första gången Frodo satte Ring på i canon var i Tom Bombadils hus:
He waited for an opportunity, when the talk was going again, and Tom was telling an absurd story about badgers and their queer ways - the he slipped the Ring on.
Men formuleringen kring detta tyder på att han redan var bekant med Ringens effekter:
Tom leaned forward and handed it back to him with a smile.
Frodo looked at it closely, and rather suspiciously (like one who has lent a trinket to a juggler). It was the same Ring, or looked the same and weighed the same: for that Ring had always seemed to Frodo to weigh strangely heavy in his hand. But something prompted him to make sure.
[...]
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.
Så det är ganska troligt att han hade försökt det på något tidigare stadium (trots Gandalfs flera varningar).