Hi jet_jockey,
I think the timescales can vary hugely depending on BA's requirements at that particular moment in time.
Personally for me the dates were as follows:
Applied Online: April 2006
Interviewed: July 2006
Sim Ride: September 2006
In Hold Pool Until: January 2007
Start Date: May 2007
However, some people I know who have been through the selection process in the last couple of years were interviewed and had there sim over 2 days and were then called with an immediate start date.
Hope this helps.