I suspect that Rubaiyat's were always manufactured as a wristlet watch. I don't think we've seen any without the bottom wire to suggest that they were ever sold as a pendant watch, unless they went by a different name (pre Rubaiyat).
They are a little different to wind, near impossible when worn on the wrist, but otherwise about the same.
My feeling is that Arde was the guy who really moved the company down the watch path, as Joseph started the J. Bulova & Co. as a jewelry wholesaler and manufacture.
I've also found previously this states that John Ballard also had a big input into the company selling watches.
'It would take the intervention of his seventeen-year-old office assistant, John Ballard, however, to fully persuade Bulova himself of the marketability of wristwatches. Hired at the age of thirteen, Ballard—who would later become the acting president of the company and a forceful proponent of continual innovation for almost fifty years—was given a large amount of watches by a client in order to resolve a debt.
Only seventeen, Ballard convinced Bulova to allow him to sell the watches, which sold quickly and profitably. This revelation, combined with his decades of experience crafting quality clocks and pocket watches, led Bulova to reorganize his business.'
What I do find really strange and a key focus to any and all research I do, is to find the watches Bulova sold between 1900 and 1916, if they did at all. We see absolutely no adverts advertising or mentioning Bulova manufacturing or selling watches, despite what has been written here about Bulova early days. There are plenty of notices about the company, but nothing really until 1918 relating to watches.