Like Akram said, I like to let the plant get around 1-2 feet before pinching the terminal bud on a young tree in pots (assuming there is no other branching), this is so I can develop the scaffold branches then as ascpete said once I have scaffold branches established around the 3rd year for me, that is when I will do pinching, sometimes it can be done the second year but when I have been forcing fruit from first year plants sometimes I get poor quality fruit that easily sour or fall off. Most of my trees this year I think I will only letting them grow and no so much pinching just to get branches what I want rather than fruit production, and some of this is because I will have to root prune next spring and I want to try and maximize next years crop after the root pruning and branch pruning.
I recently pinched a col de dama noir because I want to make it an open vase style tree in pot there are leaf buds starting to go open but I can tell they all want to go straight up so I will be tying some down for sure to get my scaffold branches set, once those scaffold branches develop I will let the next branches go out like the diagrams Ascpete has put up many times from the japanese. I think if I can train the trees like this, minor pruning every year will keep me with moderately vigorous new growth that is even and productive and only do the pinching on the branches when I want to force vegetative growth to stop and figs to form. This will all depend on how the figs are developing so we will see how it turns out, but I have high hopes for it to work well as it has worked well with other types of fruit trees.