I've written here before about beginners and seedlings and I always point out that this is not the best way for beginners to get started. If you use the search feature and use my user-name and the term 'seed' you can easily find my thoughts on the subject.
I suggest that if you are intent upon growing from seed that you should at least approach bonsai from a different direction at the same time. This way you have something to work/learn with while you are pampering your seedlings.
I assume that when you say Japanese Elm you have purchased Zelkova seeds. These should be pretty easy to grow, I have a group of them that are about 5 years old and they don't seem to be too finicky. I do suggest that you start as many as you can or at least as many as you can handle. By the time you get through the early years a percentage of them will not make it for various reasons.
No bonsai techniques are really required at first, just grow out your seedlings using sound horticultural principles. In fact the only specialized work you will do in the early years is to guide the roots into a pleasing arrangement. I do this at every re-potting, yes even seedlings, it is never too early. Since it is getting a little late in the season your first re-potting will not be likely to occur until next spring. Sometimes I will start seeds in a flat and then move them up after they have grown a bit but it is probably a little too late for you to take that approach.
My reference material indicates that stratification, while beneficial, is not strictly necessary for this species. It is noted, however, that the seed should not be allowed to dry or they may not germinate at all. Last years seed should have been stored properly and planted months ago, so that may be an issue which is another reason to plant many seeds and hope for the best.