I believe you can start introducing certain veggies at 6 months. If it is her first veggie only give her a little bit(like one sprig) just in case it bothers her. I know my Buster goes crazy for Parsley so I hope your little bunny won't get addicted like mine.
Parsley is definitely bunny safe (Italian parsley is too) and usually a hit in my experience. Definitely start slow when you introduce a new veggie, and especially if this is their first veggie. Try just one sprig the first day and see how she handles it. If you notice any GI upset, back off.