Hi Robin,
I'm pretty new to this forum, but not new to bonsai. I grow a number of Ficus species and prune some very heavily. Also been growing edible figs for some years, but I see from the level of expertise on this forum that I am just a neophyte in that area.
It would be very helpful to see the tree in question. As a general rule I agree with the comments made by other members that your tree is pretty darn small for pruning, but there are always exceptions. Also since I am new I don't know how exeperienced you are with figs or growing in general, so I ask, are you certain you have a Ficus carica and not a different species of Ficus? If it not an edible fig (carica) that also makes a big difference in whether or not to prune now. Some Ficus species are very quick growers indeed! You can always prune back growth in the future, the benefit of pruning very young is that you can control the way it will grow/progress better, but of course an always safe option if in doubt is to leave it be.
BLB