Feeding young buns!

My bun is at least ten weeks old, don't know precisely, I'm wondering about when I can start feeding her greens

Some background info, we're weaning her from unlimited grass hay only to a grass hay + young rabbit pellet mix. That's going okay, gave her bad poops a little at first which, being a new rabbit owner, scared me but I'm told it happens.

We're just passing from week one of pellet feeding.