The shoes will be here by half-past four at the latest.

I read about this inscription years ago - many years ago. I've forgotten where I read it, probably in a book I borrowed from the library, since I have never seen it referred to in one of my own books about Venice. Anyway, the book said that the inscription was in front of Quadri's caffè. I spent several fruitless hours - well, not hours, perhaps, but 'several minutes' does not convey the right amount of time - looking for the inscription. I asked at Quadri's, but, of course, they had no idea what I was talking about (my Italian is not good, either). I eventually concluded that it must be underneath the daïs that the orchestra plays on. And then I stumbled upon this: http://www.veneziamuseo.it/TERRA/San_Marco/Marco/marco_cur_sensa.htm - I was looking for information about the Festa della Sensa at the time - and so it was that I was able to find the inscription. Of course, once I'd found it, I couldn't understand how I'd missed it before. There is another inscription, currently behind the fence around the Campanile. It is interesting to learn that the zavateri had to use old leather to repair shoes or to make clogs and slippers, since new leather was reserved for the calegheri - shoe-makers. [That's how I understand it.]
Almost as interesting is the fact that the trachyte and Istrian stone pavement of the Piazza was laid in 1722 [almost an hour after the shoes were ready ] by Andrea Tirali, which means that the '1625' is an anachronism. I bet Andrea was tired when he finished! I wonder how long it took him.