Clicio The nodes on my branches are very far apart closer to the trunk. How much can I prune in the winter to encourage it to be compact.
That is a beautiful Wisteria.

Theoretically you could do a hard pruning, it will bud all over in the Spring.
I have never done that on a Wisteria, but I know it is faster to put it in the ground so it thickens faster than in a pot, and then take it off the ground and chop it.
My Wisterias are babies with very, very long arms, which I prune every two weeks or so.

onionz wrote:

Once in a bonsai pot will the trunk thicken over time or does it need to be thick when you pot it?

It thickens much faster in the ground.
But Wisterias are fast growers, so they can be cultivated in pots and still grow well.

bonsaitonight.com/2018/12/25/a-dwarf-wisteria-bonsai/

Here is my indoor wisteria a couple months later. Much trimming off the top.