Around age 12 - that is, in the midst of the Hippie culture days of the mid-60's. I recall very little from my first reading, unfortunately! But I was not alone in my love of the book, and thus it was that in high school my fellow "geeks" (the word was not used then) and I gave ourselves "Tolkien" names ("dernwyn" dates from this time) and passed notes written in Tengwar and Angethas.
Favorite Tolkien character:
Sam. He's the everyman who knows his purpose in life, and will see things through. Practical, comical, sturdy, I'd love to have him by my side!