Well we need most every tile roaded, and at size 12 we need 15 spt, so whenever that can be accomplished we add em in. +1 for the lux colony.
Edit: Well 5 worker turns for each ivory (road + movement to/from the tile) and 8 for the hill and ivory forests= 39 worker turns not counting what they are working on now. 7 workers? 8? Build warrior to sizes 6 and then another to size 7 to get all 3 mps?
At size 12, we should be using the following 9 roaded tiles:
3 irrigated cows (+10)
1 irrigated BG (+1)
3 ivory plains (-3)
2 ivory forests (-2)
That leaves 6 food for 3 specialists. And the option to use the lake for 2 food surplus so that we can make an extra worker when the box fills up if needed.
Production is 15 spt with these tiles.
Those tiles need to be roaded before we join in the workers. Other tile improvements should be made someday, but there is no hurry. (Jungles, hill, mine on ivory plains)
2 turns from now, the irrigation on the BG is ready and the curragh is ready. We then have 3 workers to build the following roads, and our city has grown to size 6.
BG (3)
Ivory plains (3x4 = 12)
Ivory forest (2x7 = 14)
cow(3)
Total 32 worker turns.
We will be adding a worker every turn, so avoiding real math:
3 (3)
4 (7)
5 (12)
6 (18)
7 (25)
7 (32) (warrior)
So if we produce 4 more workers for a total of 7 and then produce 1 warrior, we would have exactly enough worker turns to finish the roads by the time our city has gone to size 7. (so we have only 2 warriors for mp)
This is exactly enough though, chanes are good that it may not be possible to make it fit so perfectly, with the forest taking 6 turns, we probably need to stack workers there anyway, increasing the needed worker turns to 34. I think it is no problem to use 2 turns for joining the workers though.
With a total of 7 workers, we join 5 in the city, use 1 for the incense and have 1 remaining. We could then make another one at size 12 a little later by using the lake. Using the lake (2 commerce) costs only 1 science per turn, so that is better than delaying the growth and producing an extra 1 turn worker. That leaves us with 2 spare workers.
If you guys think 2 spare workers is not enough, then produce 5 more workers instead of 4 before joining them in. A 5th worker will make things easier like roading the forest in time. However, don't take it too lighly, this most likely costs us a full turn delay on research and thus pretty much our whole game.
So, either 4 or 5 more workers looks best to me. Maybe someone wants to figure out in what order exactly to build the roads.