The real figures worked out by me last week based on BALPA seniority list:
Captain 737 5yrs, C320 12yrs, C757 13yrs, C777 19yrs, C747 20yrs.
FO 757 2yrs, P777 2yrs, P747 3yrs. (But frozen first 5 years)
These are all 'ish based on 3000 seniority now. New joiner is about 3200. If retirement age goes to 60 at BA add 5 years. There are all sorts of variables though so I'm working on the above figures plus 3 years.