Wow is that cool...I LOVE that the stem still has the badge on it. Citoyen Du Monde, who I'm sure will comment, had a pink step through that was built for Mrs. Cinelli. Salmon pink and beautiful...this one is quite similar.
Hard to tell from the picture, but it looks like the "small" headbadge, 51mm tall instead of the "large" at 56mm. If it is the "small, I'd say 1958-1959, assuming the RD is original. If it is "large", again assuming an original RD, 1953-1958. But since the CInelli decal is not the lozenge, I think later is more likely than earlier. The non-Cinelli-branded crank would also be appropriate for a late 50s build.
Model B - did it come out of Germany? It seems they received the lion's share of Mod Bs in the 50s.
Uncommon fork crown, never seen a Cinelli with one like it. Cool.
Components are correct for the time.
Love the fenders, I think it would be worth it to fabricate the front tip you are missing.
One other thing, I would guess the grips could be replacements. Bone would be more appropriate.