Thank you Treebeard !
"I would have left the wire ring in place, since Chinese elm are pretty tough, and the wire won't start to create any constriction for several months."
This is what I thought but, on another forum, I was told you shouldn't repot and layer the same year So I rushed and removed the ring. But then I asked myself : I will need to take it out to put the ring back next year anyway !!!
No I won't remove it from the ground again, I will give it one year to accommodate and to know it better and next spring I will start working on the Nebari.
I think it would be a nice little broom shohin in a few years don't you think ?
One more question Chinese Elms should be in full sun right ?