When she asks to cross the road to school by herself. Well actually she's asking to walk to school by herself, so we've reached a compromise - I stop a little bit of a distance from school, let Bianca get out of the car, grab her bag and I watch her as she crosses the one road. So far so good :-).
When she mentions that she wants less presents for her birthday and instead wants some birthday money.
When she finally says: "I'm old enough now, I can go to sleep without sleepy time song". This one is a tiny bit sad really - I made up this song way back when Bianca was just a few days old and she's liked it ever since. Every night both girls would ask us to sing this to them and now it seems... Bianca is growing up.