I have written before about "Who Was Fibonacci Before He Was Fibonacci?"
I pretty much thought I had covered the list, as uncertain as it was, and it must have been no sooner than 1765. Finally I found another reputable confirmation in Keith Devlin's The Man of Numbers, but also, ... HOW HAD I MISSED THIS STATEMENT!
In one early section he writes, "He refers to himself as filius Bonacci, a Latin phrase that translates literally as 'son of Bonacci'. But Bonacci was not his father's name, so we should perhaps translate the phrase as 'of the Bonacci family'."
He then goes on to credit the origin of the present day nickname "Fibonacci" to the historian Guillaume Libri in 1838. A common attribution I had included before the long list of earlier uses provided by Heinz Lueneburg in the post linked above. Heinz goes on to opt for, "My personal pick is Flaminio dal Borgo 1765."
Ok, so very recently searching through the Devlin book again for a mention of an old problem that Fibonacci had included somewhere, I came across this line (page 128, 2nd paragraph:
The oldest abacus (calculations) books still in existence date from around 1290. On of them is livero del abbecho. Its unknown author describes it as ... (long Italian phrase ending in).. del'figluogle Bonacie da Pisa" (abacus book according to the opinion of master Leonardo Fibonacci), perhaps making it one of the earliest to make such use of Leonardo's name.
Now 1290 is way before Libri, or even Flaminio dal Borgo.... like 500 years before. So, I get the feeling we may still be waiting for another historian who will find that , for whatever family relation he sought to mean by it, we may someday come to find out that during his life, at least after he became famous throughout Europe, they did speak of this master of abacus as The Pisan, Fibonacci.
By the way, Devlin's book has a wonderful photograph of the surviving statue of Fibonacci standing amid the rubble of the bombed out central bridge in Pisa during WWII, before it was moved to the Camposanto.