Below are some dating guidelines that I compiled, and that iab added to in a previous thread. It's not the gospel, but might be helpful in dating your bike.

Late 50s – Larger head badges with dark blue paint discontinued
· 1960ish – Decals lose metallic quality silver and gold
· 1960/61 – Campy Sport RD hole no longer (occasionally) appears on rear dropout?
· 1960-62 - Wolf ear head tube lugs disappear?
· 1962 – Cinelli buys Nitor saddles
· 1962-64 – Model B occasionally equipped with Altenburger dropouts, derailleurs, and brakeset.
· 1963/64 - Alloy Cinelli bars introduced
· 1964ish – BB shell shifts from occasionally 74 to consistently 70mm?
· 1965 – Oil ports discontinued
· 1968 - 1A stem introduced
· 1968 – holes in lugs appear
· 1968ish – Brass head badge becomes aluminum
· Early 70s – fender eyelets taper off?
· 1973 – Seat post binder bolt changes?
· 1974/75 – bottle braze-ons appear?
· 1977/78 – Change of logo on stems
· 1978-81 – Change of logo on bars
I'd say the wolf ears disappeared by 1960.
The 74mm BB was 1960-64?
1946-48 were Giotto Cinellis
1948-1950 maybe 52 the seat-stay cluster is very Frejus-esque.
1950-1955 Model Bs had internal rear-brake cable guides.
Never seen a B with an oiler port.
B production went into the early 1970s.

Edit: I forgot to add, I have never seen Cinelli branded cranks (likely Magistroni) after the 50s.