I wouldn't give it to a baby, but to an adult rabbit, I like to give them sticks to chew on. I've been told sticks from apple trees taste sweet to them.
A toy that challenges her may be good every once and a while, but I would buy a hay rack to put in her cage so she'll have easy access to it. Hay is very important. My rabbit has just a wooden toy that is hung on the side of his cage for him to chew on. He also has little balls with bells in...
When my rabbit was a baby, I just fed him regular feed and hay. I refused to give him any extra vegetables or treats like carrots until he was four months, I think? I did some research online and that was what I found out. Even if that was longer than I needed to wait, better safe then sorry.