I vote for Bronze Working -> Priesthood. Below is my analysis of why I vote that way
I would have thought that would get the oracle almost as fast as ... -> priesthood -> bronze working anyway. It surely takes forever to build it with no marble and no chopping or whipping, if we have bronze we can pre-chop forests while we research priesthood.
Without settling another city or two, I will give the approximate numbers that we will see.
After learning Priesthood on Turn 69, 2275 BC, by working the PHRiver and a GHForRiv, we get 7 Hammers per turn. After some growth for 5 turns, that value can be increased to 9 Hammers per turn.
Bronze Working would come in 18 turns later.
So that gives us 5 * 7 + 13 * 9 = 35 + 117 = 152 Hammers
The claim is that by pre-chopping, we can make up for those missing 152 Hammers.
Well, a Forest chop takes 5 turns.
A Forest pre-chop will take 4 turns, but since we aren't losing Worker turns due to Worker movement, we can just total the number of Worker turns gained and use that figure directly.
If we start to research Bronze Working on Turn 61, 2475 BC, we can learn it in approximately 16-17 Turns (depending upon whether we keep working the Irrigated Grassland River square--which in the real game may even get overgrown by a Forest). But let's say it is learned in 16 Turns, because we'll want to put a focus on doing so.
Instead of building The Oracle right away, after our 3rd Settler is completed, we can build another 2 Workers.
Our 2nd Worker will take 6 turns to build, starting at the time where we have 9 turns left to go on Bronze Working. After that we can probably pump out our 3rd Worker and maybe 4th Worker by the time that we've researched Priesthood.
On Turn 77, we learn Bronze Working and start chopping with our 2 Workers.
On turn 80, we get our 3rd Worker and then realize that we can build a 4th Worker by the time that Priesthood comes in--both happening in 6 turns.
On turn 86, 1850 BC, we start work on The Oracle with no Hammers invested into it. We've just built our 4th Worker from the capitol (other cities may or may not have built one by now).
The 3 Workers that we had working for us gave us this many Worker turns:
9 + 9 + 6 = 24 Worker turns.
Each Forest chop in the fat cross gives us 30 Hammers and takes 5 Worker turns to complete.
That gives us 30 * 4.8 = 144 pre-chopped-worth of Hammers, slightly less than the 152 Hammers we get from manually building The Oracle up to this point in time.
Now, that's less Hammers than purely building The Oracle, but there are several factors at play here:
1) We will have a lot more Workers running around, since we used our Corn's excess food and small amount of base-Hammer production (1 Mined Hills square and one Forested Hills square) to make Workers instead of growing to use even more Forested Hills squares. Those Workers will help us to chop even more squares quickly, after we start work on The Oracle. We'll get considerably more Forest chops than we would with 1 Worker in the build-Oracle-first scenario, by the time that The Oracle is complete
2) Those Workers can even Mine the Grassland Hills Forest River squares for us, netting us an extra Hammer and Commerce that much sooner, at the cost of less Hammers from Forest chops
3) The build-Oracle-first scenario could also build an extra Worker or two, at the cost of raw Hammers put into The Oracle. If it did so, however, then the Workers would sit around (or would improve our 2nd and 3rd cities) for a bit longer
4) The number of Forests available are limited, but we have 15 of them in our fat cross. We might want to keep a few around for the extra Health benefit and for Forest-regrowth, but those should be more than enough to mostly-chop The Oracle: 225 Hammers (The Oracle) / 30 Hammers per Forest = 7.5 chops. So, with 6 to 7 Forest chops, we can complete The Oracle and still have many Forests available to us
Summary
The numbers are close and slightly in favour of the Priesthood-first scenario at the time of having learned both Bronze Working and Priesthood, but I am strongly leaning towards the Bronze-Working-first scenario, mostly because it is very efficient to build Workers with our excess Food, while it is pretty inefficient to grow our city only to be able to work 3 (Food + Hammer) squares, as in the Priesthood-first scenario.
We have "the excuse" of "having" to build Workers in the Bronze Working first scenario, since we are UNABLE to start manually building The Oracle, while building these Workers in the Priesthood-first scenario just gets us a few Workers that still have to sit around for 9 extra turns than they would in the Bronze-Working-first scenario, reducing their value.
If we had a lot less Forests, then the Priesthood-first option would be the way to go, as the number of Forests would be our limiting factor, but here, the number of Forests available is so high that our best bet is to get out a bunch of Workers early on and start making good use of those chops.