First, the branches in that 'nice' circle - are they in fact at different, or the same level? They really should be all at different levels (and directions, but that's a little less vital). Second, cutting the branches will cause them not to fatten, but then again, why would you want them fat? It's the trunk that needs fattening, tapering well from the bottom, and the way to get that is to leave 1-2 of the lowest branches to grow unpruned for as long as it takes to get the girth you want, and then if that branch doesn't fit with the eventual design you have for the planned tree, it can be cut flush with the trunk. When you say roots are contained in the pot, what do you mean (that none have grown down thru the drain holes yet?)? Containing the tree to a small pot when it's not yet the size or thickness you want is counterproductive, so maybe forget 'bonsai' for now in terms of the pot, apart from keeping it relatively shallow, and use a slightly taller but definitely wider one while it's growing out. I do hope you do have 1-2 good sized drain holes in the pots?

Thanks Lucy for your reply.
Yes, the branches are on just slightly different levels.
And the pots are plastic "pan" pots, 6 inch circumference, but shallow, with the regular 6 drain holes.
And yes, the roots have shown no inclination to exit the pots.
So things can continue as they are pretty much with these.
These live outdoors all year with not much fuss and green up in early Spring. I am in Northern CA where we go below freezing temps very seldom.