I did hear that an Airbus Flight Management and Guidance System (FMGS) has a different philosophy whereby the aircraft will start down automatically unless you select an altitude hold mode. But that could be total bolleaux, somebody else can advise.
That would depends what's in the ALT window. If you were lucky and came in at the right moment the crew may have already had the "descend when ready FLXXX" and you'd be ready, but do you not have to physically push it in to get descending? If not, you get a nice PFD message telling you to "DECELERATE".
Horgy