My DD is 20 weeks old and is starting to get bored and upset in the bassinet of the pram. She'll sleep in it for a short period, but once awake she's not happy.
I know it's usually advised to change at 6 months, but does depend on the individual baby. My DD is not sitting independently yet but has excellent head control.
We have a Bugaboo Cameleon.
At what age did you change yours?