The name Favre is a storied one in horological history.
Marc Favre was a serious movement designer and manufacturer. Eventually he became part of Gruen Guild, which was later Alpina Gruen Guild SA. (dissolved in 1939) This explains why Alpina movts overlap Favre ones. Identical movts will be stamped as either, but were designed and produced by Favre. Gruen was also part of Aegler (with Rolex), but dropped out in the 30's, at which time Rolex and Aegler owned Aegler outright. Favre also worked with Universal in Geneva, and this is why Universal movts are also double stamped or identical to Favre designed ones of the period.
The Favre family connection is all over, the Favre-Leuba co. being one that still resonates, despite the brand being extinct. It was born in 1882.
In 1913 Favre had a line of 9''' ladies watch movts. It is quite possible we will someday find these in the earliest Bulovas.
I have never been able to find any information as to what factory Bulova purchased in Switzerland; clearly it was geared up and ready to go, and there was probably no hiccup in production, save to re-tool for Bulova ID stampings. Bulova not only standardized the watches and parts that went into them, he designed and manufactured any and all tooling and test equipment to make sure they were standardized.
Bulova's relationship to Favre was the same as with any other ebauche supplier, (There were many that Bulova used) the blanks were modded, sometimes only with the name stamp. Bulova quickly began modding the balances of almost all its ebauches from other firms. This probably served a variety of purposes, not the least of which was importing unfinished movts to the US, which was cheaper.
I agree with Stephen on this, it is really surprising how quickly Bulova became a going concern in the watch world. He went from scratch, after working for Tiffany, to opening his own Jewellery store (1875) to owning a Swiss Factory (Bienne, 1912) to having the tooling and facilities to finish ebauches in the US, and finally to design movts from scratch and manufacture entirely in the US, to say nothing of the iconic case designs and various patents the company developed.
The earliest Bulova wristwatches will undoubtedly turn out to be ladies' models, and somewhere out there they are waiting. I suspect they will be a bit of a mish-mash of ebauches and casemakers we are as yet unaware of Bulova partnering with. The oldest watches will be pocket watches, Swiss made in the Bulova Factory, and Ancestors to the Hudson Maxim models. There may not be any name on the dial, or if there is, it may not even be Bulova, or even Rubaiyat. I suspect the movts will be stamped, but even this is uncertain.
It is no small accomplishment that Bulova at its peak was responsible for 50% of the timepiece market in North America. (1958)
What is also rarely, if ever, seen are the boudoir and table clocks Bulova made prior to concentrating on watches.
One day we will find them!