G'day Carl and welcome to Ab.com!
Like the others have said.
To grow a trees size we place it in a large container "Grow box", (could be a white styrofoam box) which allows a mass of roots to form and add size.
To keep it small, it goes into a bonsai pot when we are at the finishing stage.
Since it has been already potted I would leave it where it is.
I don't necessarily think you will get that trunk even if it does go in a box. Personally I would leave it where it is, it looks nice and will be pleasing for you to view.
I would use this already planted tree to hone your skills.
Give it a good feed, as it could be putting on more growth atm. I use dynamic lifter on all my figs.
Secondarily, I would remove all leaves except the one at the end of all the branches. If you remove the tip (uncurling new leaf) the branch will stop growing in length, by the look of your hoped pic, we need a bit more length to them. This first defoliation will also help you get started in reducing the leaf size of the fig (though is not permanent unless tip goes too). I have defoliated like this, all my figs at least 4 times this summer so far.
Once you have the leaves off, you can look at applying some wire to the branches for some curvy movement.
Hope that helped a bit, feel free to ask more questions or for me to elaborate more.
Did I just serve you at Buzzings?

Regards, Mitchell.
"It is one thing to shape a tree into form, but when you are able to convincingly deceive ones perception of reality, something much more is accomplished than just a simple bonsai."
"In a perfect world, we would all be giants and all plants Bonsai."
"Grow big, finish small."
Join Ausbonsai today Click Here! 