Bonsai is an art requiring lots of patience!
Not everyone would agree with tom about the 8-10 years. That is based on the idea of trunk chop. You let your tree baby grow until it is an actual tree with a good diameter of trunk. (A rough guideline of bonsai design says that your finished bonsai should be about six times as tall as the diameter of the trunk at the base. Therefore if you want even a six inch tall bonsai tree, you should have a trunk that is an inch in diameter. That is of course not a hard and fast rule, but gives you an idea of what tom is talking about). Once the tree has a trunk diameter you are satisfied with (realizing that once it is in a tiny bonsai pot it will never gain much more girth or at least will do so v ...e....r....y slowly), you will dig it up, trim the roots so that they fit in a large pot (not a bonsai pot) and chop the trunk off at some appropriate height, giving you a nice thick little tree stump. Then you grow it out from there and start shaping it.
Here's an example of a tree that has been treated that way:
You can see it has a nice well developed root system (important for your finished bonsai) and a good thick trunk. It is now starting to put out new growth. The new growth will become the new trunk and it will provide curvature, because it will be going off at an angle to the original trunk.
There is another alternative called clip and grow. It is similar, but you would start cutting the trunk back a little sooner, while the tree is still in the ground and growing out:
But I think most people would tell you that your tree babies are too young to start wiring and training. The first step in wiring is to know what you are aiming for. Get familiar with bonsai styles:
Study your tree and visualize what style might be appropriate for you. Looking at pictures of other trees like yours would help. For example most of the maple tree bonsais I have seen are either upright:
(notice that the way the tree canopy has been developed hides the scar of the trunk chop)
or informal upright:
I think this is what the maple lends itself to best, although anything is possible, when you really know what you are doing and with enough patience.
So once your trees are a little better developed, you may be able to start training them a little bit to the style you want. Trunks are only flexible while young. So if you are going to create trunk curve by any method except chopping or clipping, you will not want to wait the ten years. But here I am getting totally beyond what I know anything about or have ever tried.