Often I see questions on how to deal with seedlings and when to wire etcetc. So here is my way..
I grow most of my plants from very small -seed or cutting- as I sincerely believe you can get better bonsai that way. You control roots and trunk shape from the start, and therefor the final outcome. To do this, I already start working the roots and stems within the first months of the plant. As soon as there is some growth of > 10cm I put it in 1mm wire to get a basic shape in the trunk. This you can do very easily, as the sapling has no wood in it yet, and is very flexible. It will set within weeks.
Examples
Forsythia cutting: winter 2011/2012. Wired this week on the first read shoot coming of the cutting
Ligustrum spp. Cut back from a nursery pllant to the first small branch at the bottom. Wound the small branch around a bamboo stick in order to create a twisted trunk after it matures in a years time
Larche after 2 years of growth this plant was wired in a screw. Now only a small hook keeps it together to set. The bottom branches are allowed to grow freely so the tunk can fatten up
Top vriew of the same larche