What would they do?

[Belegorn]

I do not know that the Three were never used initially after they were made, or not worn. In the Silmarillion it is said

Originally Posted by Of the Rings of Power and the Third Age, p. 357

As soon as Sauron set the One Ring upon his finger they were aware of him; and they knew him, and perceived that he would be master of them, and of all that they wrought. Then in anger and fear they took off their rings. [...] they were given into the hands of the Wise who concealed them and never again used them openly while Sauron kept the Ruling Ring.

Let us keep in mind the time period when the Rings were made.

Originally Posted by RotK; Tale of the Years; The Second Age

c. 1590 The Three Rings are completed in Eregion.
c. 1600 Sauron forges the One Ring in Orodruin. He completes the Barad-dûr. Celebrimbor perceives the designs of Sauron.

There is about a 10 year span where the Elves could wear and make use of the Rings and it appears from the first quote that I've given that this is probably what they did until they perceived Sauron.

Galadriel herself went to Middle-earth during the rebellion because she "had dreams of far lands and dominions that might be her own to order as she would without tutelage." [UT, The History of Galadriel and Celeborn] Then as I mentioned before when Galadriel finally met Frodo this may have been when she come to her concluding decision about the One.

Originally Posted by Unfinished Tales; The History of Galadriel and Celeborn

It was not until two long ages more had passed , when at last all that she had desired in her youth came to her hand, the Ring of Power and the dominion of Middle-earth of which she had dreamed, that her wisdom was full grown and she rejected it