I have posted above that I think we should swap a tile next turn to the plains forest hill from the unimp'd silver (just for one turn) to get the Work Boat out 1 turn faster. Oh and by the way that extra food I was talking about. That was a mistake. Oops.
These are the turns from 24 to 28 when the Work Boat is done and after we've finished the partially built warrior (takes 1 turn).
t=24: 23/179 beakers (16 bpt); 21/26 food (7 fpt); 17/30 hammers (3 hpt) [2 imp'd sheep, unimp'd silver]
[IBT]: Them grows to size 4
t=25: 39/179 beakers (16 bpt); 2/28 food (5 fpt); 20/30 hammers (6 hpt) [2 imp'd sheep, unimp'd silver, plains forest hill]
t=26: 55/179 beakers (24 bpt); 7/28 food (6 fpt); 26/30 hammers (5 hpt) [2 imp'd sheep, imp'd silver, unimp'd silver]
[IBT]: Work Boat built, start on partially completed Warrior
t=27: 79/179 beakers (24 bpt); 13/28 food (6 fpt); 10/15 hammers with 1 overflow (5 hpt) [2 imp'd sheep, imp'd silver, unimp'd silver]
[IBT]: Warrior built.
t=28: 103/179 beakers; 19/28 food; 0/? hammers with 1 overflow
At this point I see we have two main alternatives: switching to a settler right away at size 4 or grow to size 5 and then build a settler. Each of these options has some 1-pop and 2-pop whip sub-plans, although neither plan will be finished before a forest chop came in unless we went to chop a forest before improving the second silver, which I don't recommend.
Plan A: Settler at size 4
Plan A begins a Settler on turn 28.
t=28: 103/179 beakers (21 bpt); 19/28 food (0 fpt); 0/100 hammers (12 hpt + 5 fpt) [2 imp'd sheep, imp'd silver, plains forest hill]
t=29: 124/179 beakers (21 bpt); 19/28 food (0 fpt); 17/100 hammers (10 hpt + 5 fpt) [2 imp'd sheep, imp'd silver, plains forest hill]
t=30: 145/179 beakers (24 bpt); 19/28 food (0 fpt); 32/100 hammers (7 hpt + 6 fpt) [2 imp'd sheep, imp'd silver, unimp'd silver]
t=31: 169/179 beakers (28 bpt); 19/28 food (0 fpt); 45/100 hammers (9 hpt + 6 fpt) [2 imp'd sheep, 2 imp'd silvers]
[IBT]: BW researched. We have 24 beakers for a first tier tech or 28 for a second. There's 15 overflow beakers for a first tier tech and 18 for a second.
t=32: 39 or 46/? beakers (24 or 28 bpt); 19/28 food (0 fpt); 60/100 hammers (9 hpt + 6 fpt) [2 imp'd sheep, 2 imp'd silvers]
t=33: 63 or 74/? beakers (24 or 28 bpt); 19/28 food (0 fpt); 75/100 hammers (9 hpt + 6 fpt) [2 imp'd sheep, 2 imp'd silvers]
t=34: 87 or 102/? beakers (24 or 28 bpt); 19/28 food (0 fpt); 90/100 hammers (9 hpt + 6 fpt) [2 imp'd sheep, 2 imp'd silvers]
[IBT]: Settler is built.
t=35: 111 or 130/? beakers; 19/28 food; 0/? with 3 overflow hammers
Plan B, Settler at size 5
Plan B begins by building a warrior to allow Them to grow to size 5.
t=28: 103/179 beakers (21 bpt); 19/28 food (5 fpt); 0/15 hammers with 1 overflow (7 hpt) [2 imp'd sheep, imp'd silver, plains forest hill]
t=29: 124/179 beakers (21 bpt); 24/28 food (5 fpt); 8/15 hammers (7 hpt) [2 imp'd sheep, imp'd silver, plains forest hill]
[IBT]: Them grows to size 5. Warrior built, Settler started.
t=30: 145/179 beakers (24 bpt); 1/30 food (0 fpt); 0/100 hammers (12 hpt + 4 fpt) [2 imp'd sheep, imp'd silver, unimp'd silver, plains forest hill]
t=31: 169/179 beakers (28 bpt); 1/30 food (0 fpt); 16/100 hammers (13 hpt + 4 fpt) [2 imp'd sheep, 2 imp'd silvers, plains forest hill]
[IBT]: Bronze Working researched. We have 24 beakers for a first tier tech or 28 for a second. There's 15 overflow beakers for a first tier tech and 18 for a second.
t=32: 39 or 46/? beakers (24 or 28 bpt); 1/30 food (0 fpt); 33/100 hammers (13 hpt + 4 fpt) [2 imp'd sheep, 2 imp'd silvers, plains forest hill]
t=33: 63 or 74/? beakers (24 or 28 bpt); 1/30 food (0 fpt); 50/100 hammers (13 hpt + 4 fpt) [2 imp'd sheep, 2 imp'd silvers, plains forest hill]
t=34: 87 or 102/? beakers (24 or 28 bpt); 1/30 food (0 fpt); 67/100 hammers (13 hpt + 4 fpt) [2 imp'd sheep, 2 imp'd silvers, plains forest hill]
t=35: 111 or 130/? beakers (24 or 28 bpt); 1/30 food (0 fpt); 84/100 hammers (13 hpt + 4 fpt) [2 imp'd sheep, 2 imp'd silvers, plains forest hill]
[IBT]: Settler built.
t=36
In Plan A the Settler comes out a turn earlier, but Plan B has the Settler finished and is at size 5 on turn 36, while it takes Plan A another turn to get there.
The worker finishes the second silver min on turn 31. With 1 turn moving to a forest and 3 turns chopping, the chop would come in on turn 35 with the hammers not in the box until turn 36. In both Plans the Settler comes out at least by turn 36 so the hammers would overflow onto another build. We want our hammers to go into Workers or Cheap Settlers. In Plan A we should really be growing after building a Settler so it wouldn't be an ideal time to get an influx of hammers. We could still start pre-chopping. In both plans pop whips are possible. I'll go over those for each plan below.
Plan A, with Whipping:
1-pop whip:
t=32: BW researched, revolt to Slavery
t=33: 1-pop whip Settler
t=34: Settler built.
This saves 1 turn, but trades turns of working an imp'd silver (3 turns) and a population (which grows back on t=36).
By the time we get BW we can 1-pop whip our Settler, so no 2-pop whip for this Settler.
Plan B, with Whipping
1-pop whip:
t=34: revolt to Slavery
t=35: 1-pop whip Settler
t=36: Settler is built.
The Settler comes out the same turn it would have anyway, although this time the citizen whipped was working an unimproved tile. The overflow from the Settler won't get the IMP modifier so the only reason we want this kind of overflow is if it makes the Worker that comes next done faster (depends on where the whip point is on the Worker).
2-pop whip:
t=32: BW is researched, revolt to Slavery
t=33: 2-pop whip Settler
t=34: Settler is built
This gets a Settler two turns faster than otherwise with Plan B, but takes a citizen off an improved silver mine. This gets a similar result to Plan A 1-pop whip, but is inferior because it takes longer to grow back to size 4.
Overall Notes
Chopping won't get done in time to put the hammers through our Settler modifier. If we want a Settler on turn 34 we should go with the Plan A, 1-pop whip variation. If we can wait until turn 35 we should just go straight up Plan A.
EDIT: I added a save file that you can use to look at these and other strategies. It is Sommerswerd's save with all opponents on islands. I played it through exactly the way we did up to turn 24. That way you don't have to play the beginning again each time.