How long might it take for collected cedar elms to produce root growth before the tree can be styled and placed in appropriate bonsai pots?

In a mid February dig I removed five Cedar Elms, all with 3 or 4 inch diameter trunks and an Ash which I have not yet fully identified. They are all growing in cedar boxes with good bonsai soil. When they were potted they had one or two short 1/4 inch roots and only a few hairy roots. They have all branched out nicely. My plan for all of them for the rest of the year is to keep them alive, and water and fertilize them appropriately. Removal of excessive branches and wiring will be held off till after winter arrives and their leaves drop. My question relates to how long might it take for root growth and styling to take place in their 10 x 12 inch boxes so that they would be perhaps “ready” for placement in appropriate bonsai pots?

It sounds like there are no big roots to worry about so the trees could go into bonsai pots in as little as one or two years. If the trees grow well all year, styling can begin this fall.

If there are any signs of weakness - little new growth, health problems - I’d wait another year.