Bismuth Bronze needs 2.5 as much labour (and fuel if you have no magma smelters) per bar as regular bronze because you can't make it directly from ore.
2.5? No its more like 4 times the jobs/fuel as regular bronze (or more if using goblinite instead of copper ore).
Lets add this up
Bismuth Bronze cannot be smelted directly from ore, so you must acquire the bars, requiring four jobs to smelt the tin, bismuth, and two copper ore into bars. Then another four jobs to combine all the resulting bars into b-bronze. Altogether eight jobs to get 16 bars.
Regular bronze can be smelted directly from ore, thus only requiring two smelting jobs of one tin and copper ore each to get 16 bars.
While this is true, Bismuth Bronze is less expensive to embark with when doing a "make it all yourself" embark.
Cassiterite, Native Copper, and Malachite are 6 points per ore, and Tetrahedrite is 9 (but gives you some silver), while Bismuthinite is only 3 points. This means it cost 21 embark points for 16 bismuth bronze bars (27 if using tetrahedrite), but it cost 24 points for 16 normal bronze bars (30 for tetrahedrite).
If you bring the wood to burn for this, it does become 8 wood (8 points) + 1 cassiterite (6 pts) + 1 bismuthinite (3 pts) + 2 native copper (12 pts) or 29 points for 16 bismuth bronze bars versus 6 wood (6 pts) + 2 cassiterite (12 pts) + 2 native copper (12 pts) or 30 points for 16 bronze bars. So, if you are bringing the wood, the difference is almost negligable.
If you source your wood at the embark site, however, it is still a savings of 3 embark points per 16 bars. And granite (or marble) is 3 points per boulder at embark.
Myself, I've been bringing just enough wood to get the first batch of bismuth bronze made, then making an axe to source the rest of the required wood: 1 stone (or stone block if your mason has already started) for the wood furnace, 1 stone for the smelter (can be the same stone if needed), 4 charcoal to smelt two copper, one bismuthinite and one cassiterite, 1 charcoal to make bismuth bronze bars, then 1 more charcoal to make a bismuth bronze axe. Thats 1 or 2 stone and 6 wood to start chopping more wood for fuel. Less if you have your carpenter build a training axe, but I consider that to almost be an exploit and don't do it.