Here sould be discussed the plans from this thread.
I would rather NOT whip the worker (see option b)) because the following turns seem to be stronger that way. (Using option a) we would start the 2nd worker on pop1 without the exp-bonus or we would have to grow again building a 3rd warrior...)
Why does the worker2 start without the expansive bonus? I remain BtS ignorant on many things
Nonetheless I think you are not including the overflow hammers here. The overflow hammers can be applied to a worker#2 or settler#1 on t18, and then we can change production to grow to size 2, then go back to worker:
t18: worker1 moves onto forested Grassland hill, CERN starts worker2/settler1,
t19: worker1 starts chop, CERN switch production to [workboat? barracks? warrior3? w2/s1@16] until size 2 pop
t20: worker1 coninue chop...
t21: worker1 cancel chop [saving forest for w2/s1]
t??: CERN grows to 2, restarts work on w2/s1, worker finishes forest chop = w2/s2@37
I'm not very good at doing these things without looking at the game (i'm not at my civ compy), so I don't know how long it will take CERN to grow again... but perhaps you can understand the idea still?
EDIT: I'm not saying this is better than Option 2b (or something like that).... but I think this Option 2a should be considered in the decision-making