I had a bunny about 20 years ago, no clue on the age other than it was full-grown when I got it (my parents brought it home from a shelter as a surprise, I was 7 or 8 at the time).
Gaz (my lop) was 8 weeks and Nala (my lionhead) was 7 weeks when I got them... the breeder said 7 weeks was really pushing it on being old enough, but she let me buy her and just warned me to be extra gentle 'cause I really had my heart set on getting her.